The Low-Temperature Metal-Organic Chemical Vapor Deposition (Ltmocvd) Route to Amorphous Silicon Semiconductors

Abstract

ABSTRACTPreliminary results are presented for a new approach proposed by the present investigators to solve the problem of light-induced degradation in amorphous silicon semiconductors. The approach uses low-temperature metal-organic chemical vapor deposition (LTMOCVD) of tailored organometallic precursors. The precursors employed are non-toxic, non-hazardous and easy to handle. In the present paper, a-Si:H films were grown, using argon with various hydrogen concentrations as carrier gas, in a cold-wall CVD reactor at a reactor pressure of 1-10 torr and substrate temperature in the range 300–450°C. Characterization studies were performed using x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and extended electron-energy-loss fine structure spectroscopy (EXELFS). The results of these studies showed that the films were uniform, continuous, adherent and highly pure--contaminant levels were below the detection limits of XPS. In addition, EXELFS results showed that short-range order (SRO), consisting of the same tetrahedral coordinated units found in crystalline silicon, does exist in all the amorphous samples, regardless of hydrogen concentration. However, the degree of stuctural disorder in the silicon local tetrahedral units decreased as hydrogen was added.