Exciton localization mechanisms in wurtzite/zinc-blende GaAs nanowires
Exciton localization mechanisms in wurtzite/zinc-blende GaAs nanowires
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DOI：
10.1103/physrevb.87.125304
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发表时间：
2013-03-08
影响因子：
3.7
通讯作者：
Phillips, R. T.
中科院分区：
文献类型：
--
作者：
Graham, A. M.;Corfdir, P.;Phillips, R. T.
我们研究了GaAs纳米线中激子的发射特性，该纳米线含有由锌-尖晶石和纤锌矿相之间的结构交替形成的量子盘，通过温度依赖的光致发光。在10 K的排放从一个合奏的磁盘分布在一个频带的半高宽类似于30毫电子伏，而一个单一的磁盘的发射线宽为700 μ eV。虽然盘系综发射表现出S形的温度依赖性，从单量子盘的发射遵循在整个温度范围内的带隙的温度依赖性。这表明杂质上的盘内激子局域化可以忽略不计，并且增加温度会引起激子沿着沿着线的长度从窄盘转移到厚盘。我们的观测结果表明，单晶相量子盘的发射线宽的激子与声学声子的散射率比通常报道的（Al，Ga）As/GaAs量子威尔斯的值大8倍。这种大的散射率表明纤锌矿GaAs中的电子有效质量比锌掺杂GaAs中的重得多，并且是纤锌矿GaAs的伽马（7）和伽马（8）导带之间耦合的证据。DOI：10.1103/PhysRevB.87.125304
We investigate the emission properties of excitons in GaAs nanowires containing quantum disks formed by structural alternation between the zinc-blende and wurtzite phases, by means of temperature-dependent photoluminescence. At 10 K the emission from an ensemble of disks is distributed in a band of full width at half maximum similar to 30 meV, whereas the emission linewidth for a single disk is 700 mu eV. While the disk ensemble emission exhibits an S-shaped temperature dependence, the emission from single quantum disks follows the temperature dependence of the band gap over the whole temperature range. This indicates that intradisk exciton localization on impurities is negligible and that increasing the temperature induces a transfer of excitons from narrow to thick disks along the length of the wires. Our observations of the emission linewidth for single crystal-phase quantum disks show a scattering rate of excitons with acoustic phonons eight times larger than the values usually reported for (Al, Ga) As/GaAs quantum wells. This large scattering rate demonstrates that the electron effective mass in wurtzite GaAs is much heavier than in zinc-blende GaAs and is evidence of coupling between the Gamma(7) and Gamma(8) conduction bands of wurtzite GaAs. DOI: 10.1103/PhysRevB.87.125304