Cr-induced structural phase transformation in sputter deposited poly-AlN thin film from wurtzite to rocksalt structure and their effect on the optical properties

IF 5.3 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Materials Research Bulletin Pub Date : 2024-08-13 DOI:10.1016/j.materresbull.2024.113043

{"title":"Cr-induced structural phase transformation in sputter deposited poly-AlN thin film from wurtzite to rocksalt structure and their effect on the optical properties","authors":"","doi":"10.1016/j.materresbull.2024.113043","DOIUrl":null,"url":null,"abstract":"<div>We report Cr doping-induced structural phase transformation (PT) in sputter-deposited polycrystalline-AlN thin film from wurtzite (w) to rocksalt (r) structure. Rietveld analysis shows that the steady substitution of Al ions by Cr ions in the w-AlN lattice distorts and compresses the wurtzite lattice along the c-axis. The chemical pressure exerted in the w-AlN lattice by the compression from the doped Cr ions causes the PT, similar to the high-pressure-induced PT in AlN. Post the PT, the r-Al1-xCrxN thin film continues to exhibit compressive residual stress, indicating that such sustained stress may also play a role in stabilizing the metastable r-Al1-xCrxN phase. The structural distortion and the PT also affected the optical absorption characteristics of the w-Al1-xCrxN thin films. The w-Al1-xCrxN exhibit a direct inter-band transition and the band gap (Eg) decreases from ∼ 6.06 eV for pure w-AlN to ∼ 4.15 eV for w-Al0.73Cr0.27N. After the PT, the r-Al0.61Cr0.39N thin film, on the other hand, exhibits an indirect inter-band transition with an Eg of ∼ 1.84 eV. In addition to the change in Eg, a prominent defect band appears at ∼ 4 eV at low Cr% and another band appears at ∼ 0.98 eV at higher Cr%.</div>","PeriodicalId":18265,"journal":{"name":"Materials Research Bulletin","volume":null,"pages":null},"PeriodicalIF":5.3000,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Materials Research Bulletin","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S002554082400374X","RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}

引用次数: 0

Abstract

We report Cr doping-induced structural phase transformation (PT) in sputter-deposited polycrystalline-AlN thin film from wurtzite (w) to rocksalt (r) structure. Rietveld analysis shows that the steady substitution of Al ions by Cr ions in the w-AlN lattice distorts and compresses the wurtzite lattice along the c-axis. The chemical pressure exerted in the w-AlN lattice by the compression from the doped Cr ions causes the PT, similar to the high-pressure-induced PT in AlN. Post the PT, the r-Al_1-xCr_xN thin film continues to exhibit compressive residual stress, indicating that such sustained stress may also play a role in stabilizing the metastable r-Al_1-xCr_xN phase. The structural distortion and the PT also affected the optical absorption characteristics of the w-Al_1-xCr_xN thin films. The w-Al_1-xCr_xN exhibit a direct inter-band transition and the band gap (E_g) decreases from ∼ 6.06 eV for pure w-AlN to ∼ 4.15 eV for w-Al_0.73Cr_0.27N. After the PT, the r-Al_0.61Cr_0.39N thin film, on the other hand, exhibits an indirect inter-band transition with an E_g of ∼ 1.84 eV. In addition to the change in E_g, a prominent defect band appears at ∼ 4 eV at low Cr% and another band appears at ∼ 0.98 eV at higher Cr%.

Abstract Image

查看原文

微信好友朋友圈 QQ好友复制链接

本刊更多论文

铬诱导的溅射沉积聚氮化铝薄膜从乌兹石结构到岩盐结构的结构相变及其对光学特性的影响

我们报告了在溅射沉积的多晶氮化铝薄膜中由掺杂铬引起的结构相变 (PT)，即从乌兹特（w）结构到岩盐（r）结构的转变。里特维尔德分析表明，在 w-AlN 晶格中，铝离子被铬离子稳定地取代，使钨锌晶格沿 c 轴发生扭曲和压缩。掺杂的铬离子在 w-AlN 晶格中施加的化学压力导致了 PT，这与 AlN 中的高压诱导 PT 相似。PT 发生后，r-Al1-xCrxN 薄膜继续表现出压缩残余应力，表明这种持续应力也可能在稳定可蜕变的 r-Al1-xCrxN 相方面发挥作用。结构变形和 PT 也影响了 w-Al1-xCrxN 薄膜的光学吸收特性。w-Al1-xCrxN 显示出直接的带间转变，带隙（Eg）从纯 w-AlN 的 ∼ 6.06 eV 下降到 w-Al0.73Cr0.27N 的 ∼ 4.15 eV。而在 PT 之后，r-Al0.61Cr0.39N 薄膜则出现了间接带间转变，其 Eg 为 1.84 eV。除了 Eg 的变化外，在低 Cr% 时，一个突出的缺陷带出现在 ∼ 4 eV 处，而在高 Cr% 时，另一个缺陷带出现在 ∼ 0.98 eV 处。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文去求助

来源期刊

Materials Research Bulletin 工程技术-材料科学：综合

CiteScore

9.80

自引率

5.60%

发文量

372

审稿时长

42 days

期刊介绍： Materials Research Bulletin is an international journal reporting high-impact research on processing-structure-property relationships in functional materials and nanomaterials with interesting electronic, magnetic, optical, thermal, mechanical or catalytic properties. Papers purely on thermodynamics or theoretical calculations (e.g., density functional theory) do not fall within the scope of the journal unless they also demonstrate a clear link to physical properties. Topics covered include functional materials (e.g., dielectrics, pyroelectrics, piezoelectrics, ferroelectrics, relaxors, thermoelectrics, etc.); electrochemistry and solid-state ionics (e.g., photovoltaics, batteries, sensors, and fuel cells); nanomaterials, graphene, and nanocomposites; luminescence and photocatalysis; crystal-structure and defect-structure analysis; novel electronics; non-crystalline solids; flexible electronics; protein-material interactions; and polymeric ion-exchange membranes.