Lim C B, Ajay A, Bougerol C, Lähnemann J, Donatini F, Schörmann J, Bellet-Amalric E, Browne D A, Jiménez-Rodríguez M, Monroy E
University Grenoble-Alpes, D-38000 Grenoble, France. CEA, INAC-PHELIQS, 17 av. des Martyrs, D-38000 Grenoble, France.
Nanotechnology. 2016 Apr 8;27(14):145201. doi: 10.1088/0957-4484/27/14/145201. Epub 2016 Feb 23.
This paper assesses the effects of Si doping on the properties of nonpolar m-plane GaN/AlGaN quantum wells (QWs) designed for intersubband (ISB) absorption in the far-infrared spectral range. For doping levels up to 3 × 10(12) cm(-2), structural analysis reveals uniform QWs with abrupt interfaces and no epitaxially induced defects. Cathodoluminescence spectroscopy confirms the homogeneity of the multiple QWs along the growth direction. Increasing the doping density in the QWs from 1 × 10(11) cm(-2) to 3 × 10(12) cm(-2) induces a broadening of the photoluminescence as well as a reduction of the exciton localization energy in the alloy. Also, enhancement of the ISB absorption is observed, along with a blue shift and widening of the absorption peak. The magnitude of the ISB absorption saturates for doping levels around 1 × 10(12) cm(-2), and the blue shift and broadening increase less than theoretically predicted for the samples with higher doping levels. This is explained by the presence of free carriers in the excited electron level due to the increase of the Fermi level energy.
本文评估了硅掺杂对为远红外光谱范围内的子带间（ISB）吸收而设计的非极性m面氮化镓/铝镓氮量子阱（QW）特性的影响。对于高达3×10¹² cm⁻²的掺杂水平，结构分析显示量子阱结构均匀，界面陡峭，且无外延诱导缺陷。阴极发光光谱证实了多个量子阱沿生长方向的均匀性。将量子阱中的掺杂密度从1×10¹¹ cm⁻²提高到3×10¹² cm⁻²会导致光致发光变宽以及合金中激子局域能降低。此外，还观察到ISB吸收增强，同时吸收峰发生蓝移和展宽。对于约1×10¹² cm⁻²的掺杂水平，ISB吸收的幅度达到饱和，并且对于更高掺杂水平的样品，蓝移和展宽的增加小于理论预测值。这是由于费米能级能量增加导致激发电子能级中存在自由载流子所致。
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