High-performance p-channel polycrystalline-germanium thin-film transistors via excimer laser crystallization and counter doping

High-quality polycrystalline-germanium (poly-Ge) thin films have been successfully fabricated by excimer laser crystallization (ELC). Grains as large as 1 mu m were achieved by ELC at 300 mJ/cm(2). Meanwhile, the defect-generated hole concentrations in Ge thin films were significantly reduced. Furthermore, the majority carriers could then be converted to n-type by counter doping (CD) with a suitable dose. Then, high-performance p-channel Ge thin-film transistors (TFTs) with a high on/off current ratio of up to 1.7 x 10(3) and a high field-effect mobility of up to 208 cm(2) V-1 s(-1) were demonstrated for a channel width and length both of 0.5 mu m. It was revealed that ELC combined with CD is effective for attaining highp-erformance p-channel poly-Ge TFTs. (C) 2016 The Japan Society of Applied Physics