Passivation of air-exposed AIGaAs using low frequency plasma-enhanced chemical vapor deposition of silicon nitride

摘要

The authors report on the development of a simple passivation technique of air-exposed Al_xGa_(1-x)As using (NH_4)_2S treatment and low frequency plasma-enhanced chemical vapor deposition of silicon nitride. Metal-insulator-semiconductor capacitors were fabricated on p-Al_xGa_(1-x)As substrates and characterized using capacitance-voltage and conductance-frequency measurements. Modulation of the surface potential is observed and unpinning of Fermi level is demonstrated. The minimum interface state density as estimated using conductance method is in the order of (2-3) X 10~(12) cm~(-2) eV~(-1). The passivation potential of the low frequency plasma may be explained by the high level of hydrogen bombardment of the substrate.