Impact of alloy disorder on the band structure of compressively strained GaBixAs1-x
Impact of alloy disorder on the band structure of compressively strained GaBixAs1-x
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DOI：
10.1103/physrevb.87.115104
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发表时间：
2013-03-05
影响因子：
3.7
通讯作者：
O'Reilly, Eoin P.
中科院分区：
文献类型：
--
作者：
Usman, Muhammad;Broderick, Christopher A.;O'Reilly, Eoin P.
Bi的掺入使GaAs的带隙能（E-g）大幅度降低，同时自旋轨道分裂能大幅度增加（Delta（SO）），导致Delta（SO）> E-g的条件，其预期减少产生热空穴的俄歇复合损失，由此复合电子的能量和动量-空穴对被给予被激发到自旋轨道带中的第二空穴。我们通过直接将我们的数据与室温光调制反射（PR）测量结果进行比较，从理论上研究了在（100）GaAs衬底上实验生长的GaBixAs 1-x样品的电子结构。我们的原子理论计算，与PR测量一致，确认E-g等于Delta（SO），x近似为9%。然后，我们从理论上探讨的合金无序的函数的带间跃迁能的不均匀加宽。与自旋分裂跃迁相关的加宽来自传统的合金效应，而重空穴跃迁的行为可以很好地描述使用价带反交叉模型。我们表明，对于含有8.5%和10.4%的Bi的样品，在确定一个明确的光空穴相关的跃迁能从测量的PR数据的困难是由于主机矩阵光空穴状态的显着加宽的结果，在相同的能量范围和合金中的无序存在大量的Bi共振态。我们进一步提供了定量估计的影响，超晶胞尺寸和假设的随机分布的Bi原子上的带间跃迁能量的GaBixAs 1-x。我们的计算支持在GaBixAs 1-x/GaAs界面的I型带对齐，与最近的实验结果相一致。DOI：10.1103/PhysRevB.87.115104
The incorporation of bismuth (Bi) in GaAs results in a large reduction of the band gap energy (E-g) accompanied with a large increase in the spin-orbit splitting energy (Delta(SO)), leading to the condition that Delta(SO) > E-g, which is anticipated to reduce hot-hole producing Auger recombination losses whereby the energy and momentum of a recombining electron-hole pair are given to a second hole which is excited into the spin-orbit band. We theoretically investigate the electronic structure of experimentally grown GaBixAs1-x samples on (100) GaAs substrates by directly comparing our data with room temperature photomodulated reflectance (PR) measurements. Our atomistic theoretical calculations, in agreement with the PR measurements, confirm that E-g is equal to Delta(SO) for x approximate to 9%. We then theoretically probe the inhomogeneous broadening of the interband transition energies as a function of the alloy disorder. The broadening associated with spin-split-off transitions arises from conventional alloy effects, while the behavior of the heavy-hole transitions can be well described using a valence band-anticrossing model. We show that for the samples containing 8.5% and 10.4% Bi the difficulty in identifying a clear light-hole-related transition energy from the measured PR data is due to the significant broadening of the host matrix light-hole states as a result of the presence of a large number of Bi resonant states in the same energy range and disorder in the alloy. We further provide quantitative estimates of the impact of supercell size and the assumed random distribution of Bi atoms on the interband transition energies in GaBixAs1-x. Our calculations support a type-I band alignment at the GaBixAs1-x/GaAs interface, consistent with recent experimental findings. DOI: 10.1103/PhysRevB.87.115104