The use of ternary In compounds in the active region of a diode laser allows devices to be constructed which operate at wavelengths longer than that obtainable from binary GaAs. If these In compounds are included in a structure grown on a GaAs substrate then they need to be kept thin enough (pseudomorphic) to avoid misfit dislocations which adversely affect device performance. A few lasing devices using pseudomorphic InGaAs have been reported previously (1,2) without comparison to the equivalent structure with no pseudomorphic layer. In this work two laser diode structures are compared: one containing strained InGaAs and the other identical in all respects except with unstrained GaAs in place of the strained InGaAs.
{"title":"Strained Layer InGaAs GRIN-SCH Lasers Grown by MBE","authors":"J. Ebner, T. Plant, J. R. Arthur","doi":"10.1364/qwoe.1989.tue8","DOIUrl":"https://doi.org/10.1364/qwoe.1989.tue8","url":null,"abstract":"The use of ternary In compounds in the active region of a diode laser allows devices to be constructed which operate at wavelengths longer than that obtainable from binary GaAs. If these In compounds are included in a structure grown on a GaAs substrate then they need to be kept thin enough (pseudomorphic) to avoid misfit dislocations which adversely affect device performance. A few lasing devices using pseudomorphic InGaAs have been reported previously (1,2) without comparison to the equivalent structure with no pseudomorphic layer. In this work two laser diode structures are compared: one containing strained InGaAs and the other identical in all respects except with unstrained GaAs in place of the strained InGaAs.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116041179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Peter, R. Fischer, E. Göbel, H. Liu, C. Delalande, G. Bastard, M. Voos, J. Brum, G. Weimann, W. Schlapp
During the last years the physical properties of modulation doped quantum wells (MDQW) have attracted much attention from both a device as well as from a fundamental physics point of view. With these structures a degenerate one and more component Fermi system of reduced dimensionality can be realized, and e. g. many body effects can be investigated by means of optical spectroscopy /1-4/. In this paper we report on experimental studies of the carrier density dependence of the recombination dynamics. We have investigated a 13 nm wide n-type single MDQW by means of picosecond photoluminescence (PL) spectroscopy at low temperature (T = 4K). An external voltage perpendicular to the quantum well layer can be applied via a Schottky contact (evaporated on the surface of the sample) in order to vary the electron concentration in the quantum well between ns = 0 up to about 3 • 1011 cm-2 (details are reported in ref. /2,5,6/). Consequently, we can cover the regime where excitonic recombination takes place up to densities where the optical properties are governed by a one component free carrier plasma. We thereby have avoided the crucial disadvantage of comparing different samples, where the sample to sample variations of well width, interface quality, PL efficiency etc. complicate the physical interpretation.
{"title":"Density dependence of recombination rates in a gated GaAs/AlGaAs modulation doped quantum well","authors":"G. Peter, R. Fischer, E. Göbel, H. Liu, C. Delalande, G. Bastard, M. Voos, J. Brum, G. Weimann, W. Schlapp","doi":"10.1364/qwoe.1989.mc2","DOIUrl":"https://doi.org/10.1364/qwoe.1989.mc2","url":null,"abstract":"During the last years the physical properties of modulation doped quantum wells (MDQW) have attracted much attention from both a device as well as from a fundamental physics point of view. With these structures a degenerate one and more component Fermi system of reduced dimensionality can be realized, and e. g. many body effects can be investigated by means of optical spectroscopy /1-4/. In this paper we report on experimental studies of the carrier density dependence of the recombination dynamics. We have investigated a 13 nm wide n-type single MDQW by means of picosecond photoluminescence (PL) spectroscopy at low temperature (T = 4K). An external voltage perpendicular to the quantum well layer can be applied via a Schottky contact (evaporated on the surface of the sample) in order to vary the electron concentration in the quantum well between ns = 0 up to about 3 • 1011 cm-2 (details are reported in ref. /2,5,6/). Consequently, we can cover the regime where excitonic recombination takes place up to densities where the optical properties are governed by a one component free carrier plasma. We thereby have avoided the crucial disadvantage of comparing different samples, where the sample to sample variations of well width, interface quality, PL efficiency etc. complicate the physical interpretation.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128155750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Band Structure and Optical Properties of Short Period Si/Ge Superlattices","authors":"G. Abstreiter","doi":"10.1364/qwoe.1989.wa1","DOIUrl":"https://doi.org/10.1364/qwoe.1989.wa1","url":null,"abstract":"Summary not available.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134212687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Two dimensional band gap modulation in GaAs-AlGaAs structures grown by MBE is demonstrated using several approaches. In the first method a tilted superlattice (TSL) having interface planes tilted with respect to the substrate surface is directly grown by MBE. The growth process and the growth kinetics will be described in detail. The luminescence properties of undoped quantum wells grown by the TSL method will be reported. This method has been used to produce directly by MBE quantum wire superlattices which show the effects of the 2 dimensional carrier confinement in their polarization excited luminescence spectra. These effects will be described and compared to theory. Finally, we will describe the luminescence characteristics of quantum wire and quantum box dense arrays produced by Focused Ion Beam enhanced interdiffusion in GaAs-AlAs quantum well structures. Applications of these various structures to optoelectronic devices will be discussed.
{"title":"Two Dimensional Band Gap Engineering in III-V Compounds Semiconductors: Aplications to Quantum Wire Structures and Devices.","authors":"P. Petroff","doi":"10.1364/qwoe.1989.tua1","DOIUrl":"https://doi.org/10.1364/qwoe.1989.tua1","url":null,"abstract":"Two dimensional band gap modulation in GaAs-AlGaAs structures grown by MBE is demonstrated using several approaches. In the first method a tilted superlattice (TSL) having interface planes tilted with respect to the substrate surface is directly grown by MBE. The growth process and the growth kinetics will be described in detail. The luminescence properties of undoped quantum wells grown by the TSL method will be reported. This method has been used to produce directly by MBE quantum wire superlattices which show the effects of the 2 dimensional carrier confinement in their polarization excited luminescence spectra. These effects will be described and compared to theory. Finally, we will describe the luminescence characteristics of quantum wire and quantum box dense arrays produced by Focused Ion Beam enhanced interdiffusion in GaAs-AlAs quantum well structures. Applications of these various structures to optoelectronic devices will be discussed.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134263550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Clausen, H. Craighead, J. Harbison, L. M. Schiavone, B. P. Van der Gaag, L. Florez
High resolution electron beam lithography combined with reactive ion etching has enabled the creation of GaAs structures a few tens of nanometers in lateral dimension.1 There have been several studies of luminescence from GaAs "quantum dot and wire" structures. However, reports differ as to the luminescence efficiency, peak shifts and spectral character. Photoluminescence studies of structures etched from GaAs/AlGaAs quantum well material have shown that nonradiative surface recombination typically results in no observable luminescence for quantum dots smaller than ~ 60 nm.2,3 Multiple quantum well wires have been fabricated with dimensions as small as 20 nm in cross section which still luminesce with an efficiency not degraded by the fabrication process.4 Photoluminescence measurements have indicated a spatial quantization in dots as large as 250 nm.5 Other photoluminescence measurements of various size dots show no decrease in luminescence efficiency,2 compared to unpatterned material and different spectral structure attributed to quantization effects for diameters around 60 nm.6 In contrast, Forchel et al. monitored the GaAs free exciton emission from a 4 nm thick quantum well etched into wires and observed a marked decrease in luminescence intensity with decreasing wire width.7
{"title":"Cathodoluminescence Studies of Quantum Dots Etched from Single Quantum Well GaAs/AlGaAs","authors":"E. Clausen, H. Craighead, J. Harbison, L. M. Schiavone, B. P. Van der Gaag, L. Florez","doi":"10.1364/qwoe.1989.tue6","DOIUrl":"https://doi.org/10.1364/qwoe.1989.tue6","url":null,"abstract":"High resolution electron beam lithography combined with reactive ion etching has enabled the creation of GaAs structures a few tens of nanometers in lateral dimension.1 There have been several studies of luminescence from GaAs \"quantum dot and wire\" structures. However, reports differ as to the luminescence efficiency, peak shifts and spectral character. Photoluminescence studies of structures etched from GaAs/AlGaAs quantum well material have shown that nonradiative surface recombination typically results in no observable luminescence for quantum dots smaller than ~ 60 nm.2,3 Multiple quantum well wires have been fabricated with dimensions as small as 20 nm in cross section which still luminesce with an efficiency not degraded by the fabrication process.4 Photoluminescence measurements have indicated a spatial quantization in dots as large as 250 nm.5 Other photoluminescence measurements of various size dots show no decrease in luminescence efficiency,2 compared to unpatterned material and different spectral structure attributed to quantization effects for diameters around 60 nm.6 In contrast, Forchel et al. monitored the GaAs free exciton emission from a 4 nm thick quantum well etched into wires and observed a marked decrease in luminescence intensity with decreasing wire width.7","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132772198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Some time ago a new FIR detector has been demonstrated by Levine, Choi, Bethea, Walker and Malik, which used the wavelength selective intersubband absorption and subsequent emission of electrons in a multiple quantum well (MQW) structure with an electric field applied in the direction normal to the layers /1/. A major drawback of this detector is the fact, that it is a majority carrier device. The photon-assisted field emission of electrons from the individual QW's causes positive space charge in the structure. In order to avoid a time- and optical-power dependent space charge, resulting in undesirable effects similar to those of space charge limited currents, rather high dark currents are required in order to maintain macroscopic neutrality in the system.
前不久，Levine、Choi、Bethea、Walker 和 Malik 展示了一种新的 FIR 检测器，该检测器利用多量子阱（MQW）结构中的波长选择性带间吸收和随后的电子发射，并在层/1/的法线方向施加电场。单个 QW 的电子在光子辅助场发射的作用下会在结构上产生正空间电荷。为了避免与时间和光功率相关的空间电荷导致与空间电荷受限电流类似的不良影响，需要相当大的暗电流来维持系统的宏观中性。
{"title":"A New Wavelength Selective FIR Detector with High Gain and Low Dark Currents","authors":"G. Döhler","doi":"10.1364/qwoe.1989.wb3","DOIUrl":"https://doi.org/10.1364/qwoe.1989.wb3","url":null,"abstract":"Some time ago a new FIR detector has been demonstrated by Levine, Choi, Bethea, Walker and Malik, which used the wavelength selective intersubband absorption and subsequent emission of electrons in a multiple quantum well (MQW) structure with an electric field applied in the direction normal to the layers /1/. A major drawback of this detector is the fact, that it is a majority carrier device. The photon-assisted field emission of electrons from the individual QW's causes positive space charge in the structure. In order to avoid a time- and optical-power dependent space charge, resulting in undesirable effects similar to those of space charge limited currents, rather high dark currents are required in order to maintain macroscopic neutrality in the system.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133080138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Arnot, C. Sotomayor-Torres, R. Cuscó, M. Watt, R. Glew, S. Beaumont
A comparison of the photoluminescence emission from MOCVD overgrown quantum dots (QDs) patterned in MOCVD and MBE grown starting material has been made. Before overgrowth luminescence was obtained from the QDs down to 750Å in diameter fabricated in MBE material whereas after overgrowth only the larger 3000Å QDs luminesce. However when MOCVD material is used the largest dots (3500Å) only luminesce after regrowth. With both types of material the QW emission shifts to higher energies after regrowth.
{"title":"Photoluminescence Studies of overgrown GaAs/AlGaAs MOCVD and MBE Quantum Dots..","authors":"H. Arnot, C. Sotomayor-Torres, R. Cuscó, M. Watt, R. Glew, S. Beaumont","doi":"10.1364/qwoe.1989.tua2","DOIUrl":"https://doi.org/10.1364/qwoe.1989.tua2","url":null,"abstract":"A comparison of the photoluminescence emission from MOCVD overgrown quantum dots (QDs) patterned in MOCVD and MBE grown starting material has been made. Before overgrowth luminescence was obtained from the QDs down to 750Å in diameter fabricated in MBE material whereas after overgrowth only the larger 3000Å QDs luminesce. However when MOCVD material is used the largest dots (3500Å) only luminesce after regrowth. With both types of material the QW emission shifts to higher energies after regrowth.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125839532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present a study of the optical transitions between confined particle states of strained layer quantum wells (SLQWs). SLQWs of InxGa1−xAs/InP with x ranging from 0 to 1 are an excellent system for this type of study because their strain varies systematically from −3.8%(x = 0) to +3.2%(x = 1). In previous studies we have used electro-optic techniques [1,2] and admittance spectroscopy [3] to show that most of the change with x in the band gap discontinuity between InP and InxGa1−xAs layers, takes place in the conduction band. A simple phenomenological deformation potential model, has enabled us to successfully calculate the lowest ( n = 1 ) excitonic transitions for any x and in particular to explain a type I to type II superlattice transition for x ≅ 0.2. In this study we show that in order to account for higer order transitions one has to include non-linear terms in strain and band non-parabolicity effects. Our model which contains no adjustable parameters agrees well with the observed transitions.
{"title":"Optical Transitions in Strained Layer InxGa1−xAs/InP Quantum Wells","authors":"D. Gershoni, H. Temkin, M. Panish","doi":"10.1364/qwoe.1989.wa2","DOIUrl":"https://doi.org/10.1364/qwoe.1989.wa2","url":null,"abstract":"We present a study of the optical transitions between confined particle states of strained layer quantum wells (SLQWs). SLQWs of InxGa1−xAs/InP with x ranging from 0 to 1 are an excellent system for this type of study because their strain varies systematically from −3.8%(x = 0) to +3.2%(x = 1). In previous studies we have used electro-optic techniques [1,2] and admittance spectroscopy [3] to show that most of the change with x in the band gap discontinuity between InP and InxGa1−xAs layers, takes place in the conduction band. A simple phenomenological deformation potential model, has enabled us to successfully calculate the lowest ( n = 1 ) excitonic transitions for any x and in particular to explain a type I to type II superlattice transition for x ≅ 0.2. In this study we show that in order to account for higer order transitions one has to include non-linear terms in strain and band non-parabolicity effects. Our model which contains no adjustable parameters agrees well with the observed transitions.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121948210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There is a growing interest towards understanding the effect of two-dimensional confinement on the symmetry properties of the Bloch wavefunctions of carriers in superlattices (SLs) and quantum wells (QWs). In particular, recent theoretical studies have evaluated the possibilities of obtaining direct or "pseudo-direct" Si/Ge superlattices although both constituents are indirect, through the combined effects of strain and superperiodicity [1]. Useful insights in this still scarsely documented field can be obtained from the more conventional GaAs/AlAs system, in which one of the constituents is direct and the other one is not. It has been reported recently [2,3] that such superlattices could be indirect provided that the GaAs layer was thin enough. We will show here that they can further be continuously tuned from indirect to direct by means of an externally applied electric field. This experiment and others have allowed us to demonstrate that in such superlattices the conduction minimum is a combination of X and Γ states, with a degree of admixture related to the superperiodicity. Possible mechanisms responsible for this mixing will be discussed.
{"title":"Γ-X Mixing in GaAs/AlAs Superlattices","authors":"M. Meynadier","doi":"10.1364/qwoe.1989.tud1","DOIUrl":"https://doi.org/10.1364/qwoe.1989.tud1","url":null,"abstract":"There is a growing interest towards understanding the effect of two-dimensional confinement on the symmetry properties of the Bloch wavefunctions of carriers in superlattices (SLs) and quantum wells (QWs). In particular, recent theoretical studies have evaluated the possibilities of obtaining direct or \"pseudo-direct\" Si/Ge superlattices although both constituents are indirect, through the combined effects of strain and superperiodicity [1]. Useful insights in this still scarsely documented field can be obtained from the more conventional GaAs/AlAs system, in which one of the constituents is direct and the other one is not. It has been reported recently [2,3] that such superlattices could be indirect provided that the GaAs layer was thin enough. We will show here that they can further be continuously tuned from indirect to direct by means of an externally applied electric field. This experiment and others have allowed us to demonstrate that in such superlattices the conduction minimum is a combination of X and Γ states, with a degree of admixture related to the superperiodicity. Possible mechanisms responsible for this mixing will be discussed.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125603233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To date, several experiments have demonstrated the alteration of materials’ spontaneous emission rate in cavities1-3). Altering the spontaneous emission is also interesting from the device point of view. For example, Kobayashi et al. proposed the concept of a thresholdless laser with the full confinement of spontaneously emitted photons in closed microcavities4).
{"title":"Enhanced Spontaneous Emission from GaAs Quantum Wells with Monolithic Optical Microcavities","authors":"H. Yokoyama, K. Nishi, T. Anan, H. Yamada","doi":"10.1364/qwoe.1989.md4","DOIUrl":"https://doi.org/10.1364/qwoe.1989.md4","url":null,"abstract":"To date, several experiments have demonstrated the alteration of materials’ spontaneous emission rate in cavities1-3). Altering the spontaneous emission is also interesting from the device point of view. For example, Kobayashi et al. proposed the concept of a thresholdless laser with the full confinement of spontaneously emitted photons in closed microcavities4).","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129523248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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