US 11,719,739 B2
Method for testing lifetime of surface state carrier of semiconductor
Qian Cheng, Shanghai (CN); Weiya Xie, Shanghai (CN); Ya Gao, Shanghai (CN); Yiming Chen, Shanghai (CN); Yingna Chen, Shanghai (CN); Mengjiao Zhang, Shanghai (CN); Haonan Zhang, Shanghai (CN); and Shiying Wu, Shanghai (CN)
Assigned to TONGJI UNIVERSITY, Shanghai (CN)
Appl. No. 17/275,674
Filed by TONGJI UNIVERSITY, Shanghai (CN)
PCT Filed Jul. 6, 2020, PCT No. PCT/CN2020/100429
§ 371(c)(1), (2) Date Mar. 12, 2021,
PCT Pub. No. WO2021/004430, PCT Pub. Date Jan. 14, 2021.
Claims priority of application No. 201910615736.2 (CN), filed on Jul. 9, 2019.
Prior Publication US 2022/0043049 A1, Feb. 10, 2022
Int. Cl. G01R 31/02 (2006.01); G01R 31/26 (2020.01); G01N 21/17 (2006.01); G01R 31/40 (2020.01); G01R 31/42 (2006.01); G01R 31/317 (2006.01); H02S 50/10 (2014.01); H02S 50/00 (2014.01); H02S 99/00 (2014.01)
CPC G01R 31/2642 (2013.01) [G01N 21/1717 (2013.01); G01R 31/31721 (2013.01); G01R 31/40 (2013.01); G01R 31/42 (2013.01); G01N 2021/1719 (2013.01); H02S 50/00 (2013.01); H02S 50/10 (2014.12); H02S 99/00 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A method for testing a lifetime of a surface state carrier of a semiconductor, comprising the following steps:
1) Using a narrow pulse light source with photon energy higher than a semiconductor forbidden band width to emit a light pulse, coupling the light pulse to an interior of a near-field optical probe through light path collimation, and producing, by the near-field optical probe, a photon-generated carrier on a surface of a semiconductor material under test through excitation;
2) Concentrating the excited photon-generated carrier on the surface of the semiconductor material, and conducting recombination continuously with a surface state as a recombination center, wherein a recombination rate is in direct proportion to a carrier concentration and a carrier lifetime;
3) In both carrier excitation and recombination processes in step 1) and step 2), producing a change in a lattice constant due to an electronic volume effect, producing a stress wave, and detecting a signal of the stress wave in a high-frequency broadband ultrasonic testing mode; and
4) Conducting fitting calculation on the signal of the stress wave to obtain the lifetime of the surface state carrier τc.