调制掺杂AlxGa1-xN/GaN异质结中二维电子气的光致发光
Photoluminescence related to the two dimensional electron gas in modulation-doped AlxGa1-xN/GaN heterostructures
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摘要: 研究了调制掺杂AlxGa1-xN/GaN异质结中与二维电子气 (2DEG)有关的光致发光, 发现温度 40 K时Al0.22 Ga0.78N GaN异质结中 2DEG与光激发空穴复合形成的发光峰位于 3.448 eV, 低于GaN自由激子峰 45 meV。由于AlxGa1-xN/GaN界面极强的压电极化场的影响, 光激发空穴很快扩散进GaN平带区, 导致 2DEG与光激发空穴复合几率很低。在GaN中接近Al0.22 Ga0.78N GaN界面处插入Al0.12Ga0.88N限制层用于抑制光激发空穴的扩散, 从而大大增强了2DEG发光峰的强度。还研究了 2DEG发光峰随温度和光激发强度的变化。Abstract: Photoluminescence (PL) of modulation doped Al0.22 Ga0.78 N/GaN heterostructures was investigated. The PL peak related to recombination between the two dimensional electron gases (2DEG) and photoexcited holes is located at 3.448 eV at 40 K, which is 45 meV below the free exciton (FE) emission in GaN. The intensity of the 2DEG PL peak is enhanced significantly by incorporating a thin Al0.12 Ga0.88 N layer into the GaN layer near the heterointerface to suppress the diffusion of photoexcited holes.
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