title: Oxygen-free atomic layer deposition of indium sulfide.
abstract: Atomic layer deposition (ALD) of indium sulfide (In2S3) films was achieved using a newly synthesized indium precursor and hydrogen sulfide. We obtain dense and adherent thin films free from halide and oxygen impurities. Self-limiting half-reactions are demonstrated at temperatures up to 225 °C, where oriented crystalline thin films are obtained without further annealing. Low-temperature growth of 0.89 Å/cycle is observed at 150 °C, while higher growth temperatures gradually reduce the per-cycle growth rate. Rutherford backscattering spectroscopy (RBS) together with depth-profiling Auger electron spectroscopy (AES) reveal a S/In ratio of 1.5 with no detectable carbon, nitrogen, halogen, or oxygen impurities. The resistivity of thin films prior to air exposure decreases with increasing deposition temperature, reaching <1 Ω·cm for films deposited at 225 °C. Hall measurements reveal n-type conductivity due to free electron concentrations up to 10(18) cm(-3) and mobilities of order 1 cm(2)/(V·s). The digital synthesis of In2S3 via ALD at temperatures up to 225 °C may allow high quality thin films to be leveraged in optoelectronic devices including photovoltaic absorbers, buffer layers, and intermediate band materials.
authors: Materials Science Division and ‡Chemical Sciences and Engineering Division, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors: Robert F
authors: RF
authors: McCarthy
authors: Matthew S
authors: MS
authors: Weimer
authors: Jonathan D
authors: JD
authors: Emery
authors: Adam S
authors: AS
authors: Hock
authors: Alex B F
authors: AB
authors: Martinson