Determination of carrier diffusion length in GaN
Determination of carrier diffusion length in GaN
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DOI：
10.1063/1.4905506
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发表时间：
2015-01
影响因子：
3.2
通讯作者：
S. Hafiz;Fan Zhang;M. Monavarian;V. Avrutin;H. Morkoç;Ü. Özgür;S. Metzner;F. Bertram;J. Christen;B. Gil
中科院分区：
文献类型：
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作者：
S. Hafiz;Fan Zhang;M. Monavarian;V. Avrutin;H. Morkoç;Ü. Özgür;S. Metzner;F. Bertram;J. Christen;B. Gil
采用金属有机化学气相沉积法在c面蓝宝石上生长p型和n型GaN外延层，通过光致发光（PL）和截面阴极发光（CL）测量，测定了光激发载流子沿c方向的扩散长度。所研究的样品包含一个6 nm厚的In0.15Ga0.85N活性层，覆盖500 nm的p-GaN或1500 nm的n-GaN。顶部GaN层被分步骤蚀刻，并通过上述带隙激发监测来自InGaN有源区和下垫层的PL作为顶部GaN厚度的函数在表面区域附近产生光。在光生载流子密度为4.2 × 1018 cm−3的情况下，考虑到氮化镓顶层以及活性层和底层的吸收，在295 K和15 K下，mg掺杂p型氮化镓的扩散长度分别为93±7 nm和70±7 nm，无意掺杂n型氮化镓的扩散长度分别为432±30 nm和316±30 nm。CL measurem……
Diffusion lengths of photo-excited carriers along the c-direction were determined from photoluminescence (PL) and cross-sectional cathodoluminescence (CL) measurements in p- and n-type GaN epitaxial layers grown on c-plane sapphire by metal-organic chemical vapor deposition. The investigated samples incorporate a 6 nm thick In0.15Ga0.85N active layer capped with either 500 nm p-GaN or 1500 nm n-GaN. The top GaN layers were etched in steps and PL from the InGaN active region and the underlying layers was monitored as a function of the top GaN thickness upon photo-generation near the surface region by above bandgap excitation. Taking into consideration the absorption in the top GaN layer as well as active and underlying layers, the diffusion lengths at 295 K and at 15 K were measured to be 93 ± 7 nm and 70 ± 7 nm for Mg-doped p-type GaN and 432 ± 30 nm and 316 ± 30 nm for unintentionally doped n-type GaN, respectively, at photogenerated carrier densities of 4.2 × 1018 cm−3 using PL spectroscopy. CL measurem...