Nondestructive measurements of depth distribution of carrier lifetimes in 4H-SiC thick epitaxial layers using time-resolved free carrier absorption with intersectional lights

Takashi Hirayama; Keisuke Nagaya; Akira Miyasaka; Kazutoshi Kojima; Tomohisa Kato; Hajime Okumura; Masashi Kato

doi:10.1063/5.0018080

Nondestructive measurements of depth distribution of carrier lifetimes in 4H-SiC thick epitaxial layers using time-resolved free carrier absorption with intersectional lights

Rev Sci Instrum. 2020 Dec 1;91(12):123902. doi: 10.1063/5.0018080.

Authors

Takashi Hirayama¹, Keisuke Nagaya¹, Akira Miyasaka², Kazutoshi Kojima³, Tomohisa Kato³, Hajime Okumura³, Masashi Kato¹

Affiliations

¹ Department Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan.
² Showa Denko K.K., 1-13-9, Shibadaimon, Minato, Tokyo 105-0012, Japan.
³ National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.

PMID: 33379997
DOI: 10.1063/5.0018080

Abstract

To achieve low on-state and switching losses simultaneously in SiC bipolar devices, the depth distribution of the carrier lifetime within the voltage blocking layer and the techniques used for observing the carrier lifetime distribution are important considerations. We developed a measurement system of the time-resolved free carrier absorption with intersectional lights (IL-TRFCA) for the nondestructive measurements of the depth distribution of the carrier lifetime in 4H-SiC thick epilayers. To confirm the reliability of the measurement results, we also performed TRFCA measurements to the cross section of the samples. As a result, although the lifetimes are underestimated owing to an inevitable diffusion of the carriers from the measurement region, the system was able to observe a carrier lifetime distribution up to a depth of 250 μm. Our IL-TRFCA system demonstrated a depth resolution of ∼10 μm, which is the best resolution among previously reported nondestructive measurement techniques. We consider the proposed system to be useful for the development of SiC bipolar devices.