Laser-induced homoepitaxial growth of gallium arsenide films

Abstract

Epitaxial gallium arsenide films have been deposited on single crystalline GaAs substrates of (100) orientation at 425–500 °C by ArF excimer laser-induced metalorganic chemical vapor deposition. The important process parameters include the cleanliness of the substrate surface, substrate temperature, the composition, flow rate, pressure of the reaction mixture, and the pulse energy and pulse rate of the laser. Particular attention was directed to the in situ cleaning of the substrate surface prior to the deposition process. When the AsH3/(CH3)3Ga molar ratio in the reaction mixture exceeds 10, the deposited films have a specular mirror surface and show no structural features under a scanning electron microscope. Their single crystallinity has been confirmed by transmission electron microscopy. The carrier concentration decreases with increasing AsH3/(CH3)3Ga molar ratio and with decreasing substrate temperature, as expected. The carbon concentration in the deposited films, determined by secondary ion mass spectrometry, is in the range of 5×1017 to 2×1018 cm−3.