Ni-Au/AlN/Si器件的深能级瞬态谱研究

Study on Deep-Level Transient Spectroscopy of Ni-Au/AlN/Si MIS Capacitors

对GaN器件制备过程中AlN缓冲层相关的电活性缺陷进行了C-V和深能级瞬态谱(DLTS)研究。C-V研究结果表明,制备态Ni-Au/AlN/Si MIS器件中,靠近AlN/Si界面处的掺杂浓度为4.4×1017 cm-3,明显高于Si衬底的1.4×1016 cm-3,意味着制备态样品中Al原子已经向衬底硅中扩散。采用退火工艺研究了GaN器件制备过程中的热影响以及热处理前后电活性缺陷在硅衬底中的演变情况,发现退火处理后,Al原子进一步向衬底硅中更深处扩散,扩散深度由制备态的500nm左右深入到1μm附近。DLTS研究结果发现,在Si衬底中与Al原子扩散相关的缺陷为Al-O配合物点缺陷。DLTS脉冲时间扫描表明,相比于制备态样品,退火态样品中出现了部分空穴俘获时间常数更大的缺陷,退火处理造成了点缺陷聚集,缺陷类型由点缺陷逐渐向扩展态缺陷发展。

The electrical properties of AlN with metal-insulator-semiconductor(MIS)capacitors were studied by capacitance-voltage(C-V)measurement and deep-level transient spectroscopy(DLTS).It is demonstrated that the in-diffusion of Al leads to a larger doping density of 4.4×1017 cm-3 close to the AlN/Si interface,which is quite higher than that of silicon substrate of 1.4×1016 cm-3.The thermal influence in the preparation of GaN devices and the evolution of electrical activity defects in silicon substrate before and after heat treatment were studied by annealing process.It is found that after annealing,Al atoms diffuse deeper into silicon substrate and the diffusion depth increases from 500 nm to 1 mm.DLTS results show the Alrelated defects in silicon substrate are Al-O complex point defects.The fact that the deep-level parameters(activation energy ET and hole capture cross sectionσp)change after annealing indicates that different types of Al-related complexes or clusters are formed before and after in situ annealing.DLTS pulse duration scan results show that defects with higher time constant of hole trapping appear in the annealing samples.The annealing process leads to the gathering of point defects,and there is a tendency for point defects to gather into extended defects.