Growth and characterisation of Ga_xIn_(1-x)Sb thin films for infrared detectors

摘要

Growth of Ga_xIn_(1-x)Sb (x = 0.1 to 0.5) thin films was carried out using hot wall epitaxy system on high purity quartz glasses and high resistive silicon as substrates. The source material for the growth of film was grown in the laboratory using vertical Bridgmen method in microprocessor controlled high temperature furnace. The grown films were characterized using grazing angle X-ray diffraction analysis and found to be polycrystalline in nature. XPS studies on the films showed non-stoichiometry compared to the bulk crystals. Band gap measurements using FTIR confirms the formation of energy gap in IR region, but the value does not exactly tally with the expected value of x. SEM studies on the films confirm the formation of pits on the surface which attributes to the non-stoichiometry in the films. Electrical characterization of the film, viz., Vander Pauw resistivity, Hall-mobility, surface carrier concentration, etc. measurement is under progress to study the interplay between the microstructure and electronic properties of polycrystalline semiconducting thin films. Finally Au/Ga_xIn_(1-x)Sb Schottky diodes were fabricated on the grown films and electrically characterised for IR detectors.