High-performance n-channel polycrystalline germanium thin-film transistors via continuous-wave laser crystallization and green nanosecond laser annealing for source and drain dopant activation

Abstract

High-quality polycrystalline germanium (poly-Ge) films have been successfully fabricated via the continuous-wave laser crystallization (CLC) process. Grain sizes as large as 0.8 mu m were obtained for the poly-Ge films by CLC at 5.7 W. Furthermore, the source and drain dopants could then be effectively activated by green nanosecond laser annealing (GNS-LA). Consequently, n-channel CLC Ge thin-film transistors (TFTs) with a high field-effect mobility of 576 cm(2) V-1 s(-1) were demonstrated for an effective channel width of 0.86 mu m and a channel length of 0.5 mu m. It is shown that CLC combined with GNS-LA is effective for attaining high-performance n-channel poly-Ge TFTs. (c) 2019 The Japan Society of Applied Physics