Protective coating on p-n junction of In(0.53)Ga(0.47)As/InP p-i-n planer diodes by vacuum evaporated glass.

Plasma assisted chemical vapor deposition or RF sputtering of insulators has been widely used for semiconductor devices. In spite of the low deposition temperature, the plasma induced surface damage degrades the device quality. An InGaAs surface is extremely susceptible to the plasma atmosphere and the surface damage is rather difficult to thermally anneal out at moderate temperatures. In order to avoid such damage on an InGaAs surface, a technique for protecting the p-n junction of InGaAs planar diodes using thermally evaporated glass films has been developed. A planar diode with 90microns - via junction coated with the glass film had a reverse current less than 1 nA at -20 volt. The diode showed low reverse current even after prolonged high temperature exposure (>~275C for 24 hours) in air. This technique may prove particularly useful in protecting exposed p-n junctions such as those common to junction field-effect transistors.