锗锡薄膜的分子束外延生长及退火研究  

Molecular beam epitaxy and thermal annealing investigation of germanium tin films

作　　者：林光杨 钱坤 蔡宏杰 汪建元 徐剑芳 陈松岩 李成 LIN Guangyang;QIAN Kun;CAI Hongjie;WANG Jianyuan;XU Jianfang;CHEN Songyan;LI Cheng(College of Physical Science and Technology,Xiamen University,Xiamen 361005,China)

机构地区：[1]厦门大学物理科学与技术学院,福建厦门361005

出　　处：《厦门大学学报（自然科学版）》2023年第2期243-253,共11页Journal of Xiamen University：Natural Science

基　　金：国家重点研发计划(2018YFB2200103);国家自然科学基金(62074134,62104205)。

摘　　要：无应变锗锡(GeSn)合金在Sn的摩尔组分高于8%时能够转变为直接带隙材料,适合于制备硅基光电子器件.分子束外延(MBE)在高纯度GeSn制备、Sn组分和异质界面的精确调控上具有巨大的优势.然而,由于Sn在Ge中的固溶度低(<1%)、Ge与α-Sn晶格失配大(约14.7%),高Sn组分、应变弛豫直接带隙GeSn薄膜材料的MBE制备仍是一个巨大的挑战.本文综述了MBE制备高Sn组分GeSn薄膜及弛豫GeSn薄膜压应变的相关研究.首先介绍了低温MBE技术外延高Sn组分GeSn薄膜的方法及生长应变弛豫GeSn薄膜的挑战.之后给出GeSn薄膜的快速热退火行为与厚度的依赖关系,基于临界厚度模型捋清了退火过程中GeSn薄膜的应变弛豫与Sn偏析的竞争机制;最后介绍了快速热退火对GeSn薄膜发光特性的影响,提出采用快速热退火制备应变弛豫的Sn组分渐变GeSn异质结,通过载流子自限制增强MBE生长GeSn薄膜的光致发光强度.Unstrained germanium tin(GeSn)is capable of transforming to a direct bandgap material at a Sn content above~8%mole ratio,thus behaving suitably as a promising material for silicon-based optoelectronic devices.Meanwhile,molecular beam epitaxy(MBE)secures a great advantage in fabrication of high-purity GeSn and precisely controls Sn content in GeSn and acquisition of sharp interfaces between GeSn heterojunctions.However,due to low solid solubility of Sn in Ge(<1%)and large lattice mismatch betweenα-Sn and Ge(~14.7%),the fabrication of strain-relaxed direct-bandgap GeSn materials by MBE remains as a big challenge.In this paper,MBE of high-Sn-content GeSn and strain relaxion of the compressive strain in GeSn is reviewed.First,the growth of fully strained GeSn with high Sn content and challenges of growing strain-relaxed GeSn films by low-temperature MBE are introduced.The relaxation of the compressive strain in GeSn by rapid thermal annealing(RTA)is then summarized.Based on critical thickness model,the competitive behavior between strain relaxation and Sn segregation in the GeSn film during thermal annealing is clarified.Finally,the influence of RTA on the luminescence properties of GeSn is investigated.A Sn-content-gradient GeSn heterojunction with strain relaxation fabricated by RTA,which enables spontaneous carrier confinement in surface region of GeSn,is proposed to enhance the photoluminescence intensity of MBE-grown GeSn.

关 键 词：锗锡 分子束外延 非晶化 应变弛豫 临界层厚度 退火 光致发光 

分 类 号：TN304.054[电子电信—物理电子学]