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Impacts of hydrogen annealing on the carrier lifetimes in p-type 4H-SiC after thermal oxidation

Authors :
Ruijun Zhang
Rongdun Hong
Jingrui Han
Hungkit Ting
Xiguang Li
Jiafa Cai
Xiaping Chen
Deyi Fu
Dingqu Lin
Mingkun Zhang
Shaoxiong Wu
Yuning Zhang
Zhengyun Wu
Feng Zhang
Source :
Chinese Physics B. 32:067205
Publication Year :
2023
Publisher :
IOP Publishing, 2023.

Abstract

Thermal oxidation and hydrogen annealing were applied on a 100 μm thick Al-doped p-type 4H-SiC epitaxial wafer to modulate the minority carrier lifetime, which was investigated by microwave photoconductive decay (μ-PCD). The minority carrier lifetime decreased after each thermal oxidation. On the contrary, with the hydrogen annealing time increasing to 3 hours, the minority carrier lifetime increased from 1.1 μs (as-grown) to 3.14 μs and then saturated after the annealing time reached 4 hours. The increase of surface roughness from 0.236 nm to 0.316 nm may also be one of the reasons for limiting the further improvement of the minority carrier lifetimes. Moreover, the whole wafer mappings of minority carrier lifetimes before and after hydrogen annealing were measured and discussed. The average minority carrier lifetime was up to 1.94 μs and non-uniformity of carrier lifetime reached 38% after 4-hour hydrogen annealing. The increasing minority carrier lifetimes could be attributed to the double mechanisms of excess carbon atoms diffusion caused by selective etching of Si atoms and passivation of deep-level defects by hydrogen atoms.

Subjects

Subjects :
General Physics and Astronomy

Details

ISSN :
16741056
Volume :
32
Database :
OpenAIRE
Journal :
Chinese Physics B
Accession number :
edsair.doi...........e95e56b6303ef241beb1c5a991225654
Full Text :
https://doi.org/10.1088/1674-1056/ac89db