Variation In Gaas Surface Oxide Desorption Temperature As A Function of Shuttered Aluminum Oven Temperature

A variation in the thermal desorption temperature of surface oxides as a function of shuttered aluminum oven temperature has been observed for GaAs substrate material prepared for molecular-beam epitaxy (MBE) using two different wet-etch processes. A novel temperature calibration technique was developed to determine the absolute thermal desorption temperature. The observed thermal desorption temperature with a cool shuttered aluminum oven displayed no variation and was consistent with the currently accepted value of 582 °C. However, experimental results indicate that the thermal desorption temperature with a hot shuttered aluminum oven is substantially greater (630–650 °C) than the currently accepted value. It is suggested that aluminum species present on the shutter desorb and react with the surface gallium oxide to form a more refractory surface oxide.