Wafer-Scale Synthesis of WS_(2)Films with In Situ Controllable p-Type Doping by Atomic Layer Deposition

Wafer-scale synthesis of p-type TMD films is critical for its commercialization in next-generation electro/optoelectronics.In this work,wafer-scale intrinsic n-type WS_(2)films and in situ Nb-doped p-type WS_(2)films were synthesized through atomic layer deposition(ALD)on 8-inchα-Al_(2)O_(3)/Si wafers,2-inch sapphire,and 1 cm^(2)GaN substrate pieces.The Nb doping concentration was precisely controlled by altering cycle number of Nb precursor and activated by postannealing.WS_(2)n-FETs and Nb-doped p-FETs with different Nb concentrations have been fabricated using CMOS-compatible processes.X-ray photoelectron spectroscopy,Raman spectroscopy,and Hall measurements confirmed the effective substitutional doping with Nb.The on/off ratio and electron mobility of WS_(2)n-FET are as high as 105 and 6.85 cm^(2)V^(-1)s^(-1),respectively.In WS_(2)p-FET with 15-cycle Nb doping,the on/off ratio and hole mobility are 10 and 0.016 cm^(2)V^(-1)s^(-1),respectively.The p-n structure based on n-and p-type WS_(2)films was proved with a 10^(4)rectifying ratio.The realization of controllable in situ Nb-doped WS_(2)films paved a way for fabricating wafer-scale complementary WS_(2)FETs.