We investigated the structural characteristics and defect states of intrinsic GaN epi-layers in a high power device structures grown on GaN and sapphire substrates by metal–organic chemical vapor deposition (MOCVD). From X-ray diffraction, Raman spectroscopy, and photoluminescence measurements, the structural properties of the GaN epi-structures were improved clearly using GaN substrates. Through optical conductance deep level transient spectroscopy analysis, four traps were observed in all the GaN layers. The activation energies of these traps were 0.93 eV (H1), 0.61 eV (H2), 0.50 eV (H3), and 0.2 eV (H4) above the valance band edge, and their capture cross-sections were 3.41 × 10^–14 cm² (H1), 3.04 × 10^–14 cm² (H2), 1.35 × 10^–12 cm² (H3) and 2.90 × 10^–16 cm² (H4), respectively. The origins of the H4 and H1 traps may be related to gallium vacancy (V_Ga) and V_Ga-related defects, and the H2 and H3 traps were from nitrogen vacancy (V_N). The total defect density of GaN epi-layers estimated using the space charge limited current method was reduced to 1.18 × 10¹⁵ cm⁻³ on GaN substrates from about 1.52 × 10¹⁷ cm⁻³ on sapphire substrates.

我们通过金属有机化学气相沉积 (MOCVD) 在 GaN 和蓝宝石衬底上生长的高功率器件结构中研究了本征 GaN 外延层的结构特征和缺陷状态。通过 X 射线衍射、拉曼光谱和光致发光测量，使用 GaN 衬底明显改善了 GaN 外延结构的结构特性。通过光导深能级瞬态光谱分析，在所有 GaN 层中观察到四个陷阱。这些陷阱的活化能在价带边缘上方分别为 0.93 eV (H1)、0.61 eV (H2)、0.50 eV (H3) 和 0.2 eV (H4)，捕获截面为 3.41 × 10 ^–14 cm ² (H1), 3.04 × 10 ^–14 cm ² (H2), 1.35 × 10^–12 cm ² (H3) 和 2.90 × 10 ^–16 cm ² (H4)，分别。H4和H1陷阱的起源可能与镓空位（V _Ga）和V _Ga相关缺陷有关，而H2和H3陷阱来自氮空位（V _N）。使用空间电荷限制电流方法估计的GaN外延层的总缺陷密度从蓝宝石衬底上的约1.52×10 ¹⁷  cm ^-3降低到GaN衬底上的1.18×10 ¹⁵  cm ^-3。