C. L. César, M.N. Islam, R. Feldman, R. Spitzer, R. F. Austin, A. DiGiovanni, J. Shah, J. Orenstein
We have grown HgCdTe/CdTe Multiple Quantum Wells (MQW) with the lowest transition near 3 µm, and we have observed room temperature confinement and photoluminescence. HgCdTe/CdTe MOW’S of different compositions can be used over the entire infrared range, since the material is lattice matched from 0 to 1.5 eV. The importance of the 3 µm region comes from the possibility of a communications system operating with fluoride fibers. The MQW was grown by MBE with 50 periods of 100 A of Hg0.15Cd0.85Te barriers and 50 A of Hg0.73Cd0.27Te wells (1). Transmission Electron Microscopy (TEM) and X-ray data confirm very little interdiffusion and high reproducibility of layer thickness. The thick barriers are necessary for strong confinement, especially for the light hole. Therefore we can see the heavy and light hole to conduction band transitions. The separation between these two transitions is mainly determined by the value of the valence band offset (VBO) between HgTe/CdTe, a controversial parameter with reported values ranging from 40 to 400 meV (2), and suggestions of being temperature dependent. Our data support a value near 400 mev which has little or no temperature dependence.
{"title":"Room Temperature Confinement and Photoluminescence in HgCdTe Multiple Quantum Wells","authors":"C. L. César, M.N. Islam, R. Feldman, R. Spitzer, R. F. Austin, A. DiGiovanni, J. Shah, J. Orenstein","doi":"10.1364/qwoe.1989.mc5","DOIUrl":"https://doi.org/10.1364/qwoe.1989.mc5","url":null,"abstract":"We have grown HgCdTe/CdTe Multiple Quantum Wells (MQW) with the lowest transition near 3 µm, and we have observed room temperature confinement and photoluminescence. HgCdTe/CdTe MOW’S of different compositions can be used over the entire infrared range, since the material is lattice matched from 0 to 1.5 eV. The importance of the 3 µm region comes from the possibility of a communications system operating with fluoride fibers. The MQW was grown by MBE with 50 periods of 100 A of Hg0.15Cd0.85Te barriers and 50 A of Hg0.73Cd0.27Te wells (1). Transmission Electron Microscopy (TEM) and X-ray data confirm very little interdiffusion and high reproducibility of layer thickness. The thick barriers are necessary for strong confinement, especially for the light hole. Therefore we can see the heavy and light hole to conduction band transitions. The separation between these two transitions is mainly determined by the value of the valence band offset (VBO) between HgTe/CdTe, a controversial parameter with reported values ranging from 40 to 400 meV (2), and suggestions of being temperature dependent. Our data support a value near 400 mev which has little or no temperature dependence.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"11 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":"121753841","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}
I. Bar-Joseph, J. Zucker, B. Miller, U. Koren, D. Chemla
Quantum well modulators require strict control over the wavelength of the exciton transition in order to minimize insertion loss and maximize voltage sensitivity at the desired wavelength of operation. Within the quaternary material system In x Ga1− x As y P1− y , there are two parameters which can be varied in order to tune the bandgap: the thickness of the quantum well layer and its composition. Tuning the bandgap by means of well size alone is of limited usefulness since the rate at which the exciton energy shifts with field drastically decreases as well width decreases 1. In this paper, we demonstrate for the first time that the compositional flexibility of quaternary quantum wells can be used to obtain field-induced shifts larger than those obtainable in InGaAs quantum wells, yielding enhanced electroabsorption and electrorefraction. We show that quaternary devices can fill a serious need for quantum well optical modulators in the wavelength range 1.3 µm to 1.55 µm for optical communications.
量子阱调制器需要严格控制激子跃迁的波长，以最小化插入损耗和最大化所需工作波长下的电压灵敏度。在四元材料体系In x Ga1−x As y P1−y中，有两个参数可以改变以调整带隙:量子阱层的厚度及其组成。由于激子能量随场移动的速率随着阱宽度的减小而急剧减小，因此仅通过阱尺寸来调节带隙的作用有限。在本文中，我们首次证明了四元量子阱的组成灵活性可以用来获得比InGaAs量子阱更大的场致位移，从而产生增强的电吸收和电折射。我们表明，在波长范围为1.3µm至1.55µm的光通信中，第四元器件可以满足对量子阱光调制器的严重需求。
{"title":"Compositional Dependence of the Quantum Confined Stark Effect in Quaternary Quantum Wells","authors":"I. Bar-Joseph, J. Zucker, B. Miller, U. Koren, D. Chemla","doi":"10.1364/qwoe.1989.tub1","DOIUrl":"https://doi.org/10.1364/qwoe.1989.tub1","url":null,"abstract":"Quantum well modulators require strict control over the wavelength of the exciton transition in order to minimize insertion loss and maximize voltage sensitivity at the desired wavelength of operation. Within the quaternary material system In\u0000 x\u0000 Ga1−\u0000 x\u0000 As\u0000 y\u0000 P1−\u0000 y\u0000 , there are two parameters which can be varied in order to tune the bandgap: the thickness of the quantum well layer and its composition. Tuning the bandgap by means of well size alone is of limited usefulness since the rate at which the exciton energy shifts with field drastically decreases as well width decreases 1. In this paper, we demonstrate for the first time that the compositional flexibility of quaternary quantum wells can be used to obtain field-induced shifts larger than those obtainable in InGaAs quantum wells, yielding enhanced electroabsorption and electrorefraction. We show that quaternary devices can fill a serious need for quantum well optical modulators in the wavelength range 1.3 µm to 1.55 µm for optical communications.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"19 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":"121812458","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}
Optical experiments in GaAs-GaAlAs superlattices under electric fields show the formation of a Stark ladder and the gradual localization of the electronic states, which at very high fields become confined to individual quantum wells.
{"title":"Stark Localization and Optical Properties of Superlattices Under an Electric Field","authors":"E. E. Méndez","doi":"10.1364/qwoe.1989.ma1","DOIUrl":"https://doi.org/10.1364/qwoe.1989.ma1","url":null,"abstract":"Optical experiments in GaAs-GaAlAs superlattices under electric fields show the formation of a Stark ladder and the gradual localization of the electronic states, which at very high fields become confined to individual quantum wells.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"108 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":"124236292","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}
The effects of biaxial strain on the band-structure of III-V semiconductors have been investigated theoretically1,2 and experimentally3. These effects offer new degrees of freedom for heterostructure design, so-called "band-structure engineering4." In particular, when III-V semiconductors are biaxially strained, the heavy- and light-hole bands become non-degenerate, and anisotropic. The valence-band configuration that arises from biaxial tensile strain is particularly well-suited for devices that involve optical absorption. Tensile strain and the quantum size effect (QSE) of a square potential well have the opposite effect on hole energy at k=0, and if the appropriate material parameters and structural dimensions are chosen, the heavy and light-hole eigenenergies of the QW will coincide. Equivalent heavy- and light-hole excitonic resonances will result in a larger absorption coefficient5, which can improve the performance of photodiodes and high speed optical modulators6. In addition, the capability to tailor the relative energies of the heavy- and light-hole could lead to new devices that exploit the different polarization-selection rules for the heavy- and light-hole excitonic transitions6,7. In this presentation we report on the growth and photoluminescence of strained GaAsP/ALGaAs single QW′S. The combined effects of biaxial tensile strain and QSE on the hole eigenenergies will be clearly demonstrated.
{"title":"Hole eigenenergies in GaAsP/AlGaAs single quantum wells with biaxial tensile strain","authors":"D. C. Bertolet, J. Hsu, K. Lau","doi":"10.1364/qwoe.1989.tue7","DOIUrl":"https://doi.org/10.1364/qwoe.1989.tue7","url":null,"abstract":"The effects of biaxial strain on the band-structure of III-V semiconductors have been investigated theoretically1,2 and experimentally3. These effects offer new degrees of freedom for heterostructure design, so-called \"band-structure engineering4.\" In particular, when III-V semiconductors are biaxially strained, the heavy- and light-hole bands become non-degenerate, and anisotropic. The valence-band configuration that arises from biaxial tensile strain is particularly well-suited for devices that involve optical absorption. Tensile strain and the quantum size effect (QSE) of a square potential well have the opposite effect on hole energy at k=0, and if the appropriate material parameters and structural dimensions are chosen, the heavy and light-hole eigenenergies of the QW will coincide. Equivalent heavy- and light-hole excitonic resonances will result in a larger absorption coefficient5, which can improve the performance of photodiodes and high speed optical modulators6. In addition, the capability to tailor the relative energies of the heavy- and light-hole could lead to new devices that exploit the different polarization-selection rules for the heavy- and light-hole excitonic transitions6,7. In this presentation we report on the growth and photoluminescence of strained GaAsP/ALGaAs single QW′S. The combined effects of biaxial tensile strain and QSE on the hole eigenenergies will be clearly demonstrated.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"21 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114025277","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}
An integrated low power optical device with cascadable properties is essential for general purpose optical processing systems. We propose and demonstrate such a device by placing an intrinsic GaAs/AlGaAs multiquantum well structure in the base collector region of an n- p-i-n heterojunction bipolar transistor. A gain of 50 is obtained by the MBE grown devices and efficient switching occurs due to the amplification of the negative resistance region of the exciton based photocurrent.
{"title":"Demonstration of an Integrated Multiquantum Well Heterojunction Bipolar Transistor with Gain for Efficient Low Power Optical Switching","authors":"S. Hong, W. Li, J. Oh, P. Bhattacharya, J. Singh","doi":"10.1364/qwoe.1989.tub6","DOIUrl":"https://doi.org/10.1364/qwoe.1989.tub6","url":null,"abstract":"An integrated low power optical device with cascadable properties is essential for general purpose optical processing systems. We propose and demonstrate such a device by placing an intrinsic GaAs/AlGaAs multiquantum well structure in the base collector region of an n- p-i-n heterojunction bipolar transistor. A gain of 50 is obtained by the MBE grown devices and efficient switching occurs due to the amplification of the negative resistance region of the exciton based photocurrent.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"8 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":"123013900","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}
M. Wegener, I. Bar-Joseph, T. Chang, J. Kuo, D. Chemla
Remarkable changes in the absorption spectrum of n-type modulation doped quantum wells (QW) are produced by varying the electron concentration inside the QW in field effect structures1,2. In the vicinity of the gap, the dominant process is phase space filling. It results in a bleaching of the exciton resonances and a net blue shift of the absorption edge, similar to the Bumstein-Moss shift seen in bulk materials. So far the effect was only demonstrated on single QW, where the carriers were moved in the plan, in and out of the deplition region of a Schottky contact3,4. In this paper we present and demonstrate a novel concept of electric field driven electron transfer in and out of a multiple period QW structure by providing a reservoir of charges in close proximity to each QW. We report measurements of the differential absorption and the refraction associated with this electron transfer in a 10 Reservoir-QW period.
{"title":"Electro-Absorption and Refraction by Electron Transfer in Asymmetric Modulation-doped Multiple Quantum Well Structures.","authors":"M. Wegener, I. Bar-Joseph, T. Chang, J. Kuo, D. Chemla","doi":"10.1364/qwoe.1989.wb2","DOIUrl":"https://doi.org/10.1364/qwoe.1989.wb2","url":null,"abstract":"Remarkable changes in the absorption spectrum of n-type modulation doped quantum wells (QW) are produced by varying the electron concentration inside the QW in field effect structures1,2. In the vicinity of the gap, the dominant process is phase space filling. It results in a bleaching of the exciton resonances and a net blue shift of the absorption edge, similar to the Bumstein-Moss shift seen in bulk materials. So far the effect was only demonstrated on single QW, where the carriers were moved in the plan, in and out of the deplition region of a Schottky contact3,4. In this paper we present and demonstrate a novel concept of electric field driven electron transfer in and out of a multiple period QW structure by providing a reservoir of charges in close proximity to each QW. We report measurements of the differential absorption and the refraction associated with this electron transfer in a 10 Reservoir-QW period.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"69 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":"124727843","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. Brown, C. Parker, T. Sollner, C.I. Huang, C. E. Stutz
Recent optical experiments have directly measured the quasibound-state lifetime in resonant-tunneling structures [1]. The results indicate that this lifetime is close to that predicted by the coherent model of the process. The present paper deals with the effect of this lifetime on the electrical response of the double-barrier diode at high frequencies.
{"title":"The Effect of Quasibound State Lifetime on the Speed of Resonant-Tunneling Diodes","authors":"E. Brown, C. Parker, T. Sollner, C.I. Huang, C. E. Stutz","doi":"10.1364/qwoe.1989.wd4","DOIUrl":"https://doi.org/10.1364/qwoe.1989.wd4","url":null,"abstract":"Recent optical experiments have directly measured the quasibound-state lifetime in resonant-tunneling structures [1]. The results indicate that this lifetime is close to that predicted by the coherent model of the process. The present paper deals with the effect of this lifetime on the electrical response of the double-barrier diode at high frequencies.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"8 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":"124325745","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}
Recently, intersubband relaxation in modulation doped GaAs/Al x Ga 1−x As multiple quantum well structures (MDMQWS) has been observed directly by an infrared bleaching technique [1,2]. The intersubband time constants determined experimentally are surprisingly long (≈ 10 ps). But, as well width increases, electron lifetimes decrease. A well width change from 47 Å to 59 Å results in approximately a factor of two decrease in relaxation time.
最近，通过红外漂白技术直接观察到调制掺杂GaAs/Al x ga1−x As多量子阱结构(MDMQWS)的子带间弛豫[1,2]。实验确定的子带间时间常数长得惊人(≈10 ps)。但是，随着宽度的增加，电子寿命减少。井宽从47 Å到59 Å的变化导致松弛时间减少了大约两倍。
{"title":"Effects Of Modulation Doping On Intersubband Relaxation By Polar Optical Phonons In Multiple Quantum Well Structures","authors":"J. Educato, A. Sugg, J. Leburton","doi":"10.1364/qwoe.1989.wb5","DOIUrl":"https://doi.org/10.1364/qwoe.1989.wb5","url":null,"abstract":"Recently, intersubband relaxation in modulation doped GaAs/Al\u0000 x\u0000 Ga\u0000 1−x\u0000 As multiple quantum well structures (MDMQWS) has been observed directly by an infrared bleaching technique [1,2]. The intersubband time constants determined experimentally are surprisingly long (≈ 10 ps). But, as well width increases, electron lifetimes decrease. A well width change from 47 Å to 59 Å results in approximately a factor of two decrease in relaxation time.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"30 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":"122287860","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}
Recently the characteristic optical absorption of quantum well structures under the influence of an electron (or electron-hole) plasma has attracted much attention in both modulation doped structures1,2 and optically non-linear devices3. We present here the first direct experimental evidence of room temperature excitonic recovery in a depletion mode selectively doped GaAs single quantum well. Quenching of the excitonic resonance is achieved in this type of structure when the electron Fermi level in the quantum well exceeds the energy of the nz=1 sub-band, as the states normally available for absorption are filled3. The carrier concentration in the quantum well is varied by a pn junction, effectively enabling the transition from a doped to an undoped quantum well to be observed. Mesa etched photodiodes and slab waveguide structures are considered in this work and both reveal the recovery of an excitonic peak. The modulation of absorption achieved is Δα ≈8000cm−1.
{"title":"Modulation of Excitonic Quenching in a Selectively Doped Single Quantum Well","authors":"C. Tombling, M. Stallard, J. Roberts","doi":"10.1364/qwoe.1989.pd3","DOIUrl":"https://doi.org/10.1364/qwoe.1989.pd3","url":null,"abstract":"Recently the characteristic optical absorption of quantum well structures under the influence of an electron (or electron-hole) plasma has attracted much attention in both modulation doped structures1,2 and optically non-linear devices3. We present here the first direct experimental evidence of room temperature excitonic recovery in a depletion mode selectively doped GaAs single quantum well. Quenching of the excitonic resonance is achieved in this type of structure when the electron Fermi level in the quantum well exceeds the energy of the nz=1 sub-band, as the states normally available for absorption are filled3. The carrier concentration in the quantum well is varied by a pn junction, effectively enabling the transition from a doped to an undoped quantum well to be observed. Mesa etched photodiodes and slab waveguide structures are considered in this work and both reveal the recovery of an excitonic peak. The modulation of absorption achieved is Δα ≈8000cm−1.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"50 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":"115113633","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}
It is numerically confirmed that the third-order optical susceptibility χ(3)(ω;–ω,ω,–ω) is enhanced by the mesoscopically enhanced transition dipole moment of excitons in CuCl quantum spheres (QS's) but it is not in GaAs QS's and it is marginal for CdS QS's.
{"title":"Excitonic Optical Nonlinearity in Semiconductor Quantum Spheres","authors":"T. Hiroshima, E. Hanamura","doi":"10.1364/qwoe.1989.tua4","DOIUrl":"https://doi.org/10.1364/qwoe.1989.tua4","url":null,"abstract":"It is numerically confirmed that the third-order optical susceptibility χ(3)(ω;–ω,ω,–ω) is enhanced by the mesoscopically enhanced transition dipole moment of excitons in CuCl quantum spheres (QS's) but it is not in GaAs QS's and it is marginal for CdS QS's.","PeriodicalId":205579,"journal":{"name":"Quantum Wells for Optics and Optoelectronics","volume":"1 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":"129727025","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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