Influence of Fe in the buffer layer on the laser lift-off of AlGaN/GaN HEMT film: phenomena and mechanism
Author(s): Guo, F (Guo, Fen); Wang, Q (Wang, Quan); Xiao, HL (Xiao, Hongling); Jiang, LJ (Jiang, Lijuan); Li, W (Li, Wei); Feng, C (Feng, Chun); Wang, XL (Wang, Xiaoliang); Wang, ZG (Wang, Zhanguo)
Source: SEMICONDUCTOR SCIENCE AND TECHNOLOGY Volume: 35 Issue: 9 Article Number: 095024 DOI: 10.1088/1361-6641/ab9d33 Published: SEP 2020
Abstract: In this paper, a study is presented of the effect of Fe in the buffer layer on the laser lift-off (LLO) of GaN high electron mobility transistors (HEMTs). AlGaN/GaN HEMTs grown on Fe-doped and unintentionally doped buffer layers were separated from sapphire substrates using a 248 nm KrF excimer laser lift-off system. We analyzed the variations of the crystal characteristics, two-dimensional electron gas (2DEG) characteristics and the strain state of AlGaN/GaN HEMT films before and after LLO by the x-ray diffraction, Hall and Raman methods. The measurement of the distribution of elemental Fe in the GaN buffer layer was performed by secondary ion mass spectroscopy. The results show that a peak Fe concentration of 9.56 x 10(18)cm(-3)appears at the interface. Moreover, the crystal quality and 2DEG characteristics of the Fe-doped GaN film obviously degenerated, with the formation of micro-cracks under the threshold laser separation energy density (Es). In this case, the threshold laser damage energy density (E-D) was used to measure the laser damage tolerance of GaN in LLO. The analysis considers that additional laser absorption centers, induced by the Fe impurity energy level, coupled with a large residual stress of up to 1.0763 GPa in Fe-doped GaN, reduced the threshold laser damage energy density (E-D).
Accession Number: WOS:000560442700001
ISSN: 0268-1242
eISSN: 1361-6641
Full Text: https://iopscience.iop.org/article/10.1088/1361-6641/ab9d33