R. Dimitrov et al., Influence of oxygen and methane plasma on the electrical properties of undoped AlGaN/GaN heterostructures for high power transistors, SOL ST ELEC, 44(8), 2000, pp. 1361-1365
Plasma-induced damage often reduces the electrical and optical performance
and the lifetime of compound semiconductor devices. We have investigated th
e effect of oxygen and methane reactive ion etching plasma on the electrica
l characteristics of nominally undoped GaN/Al0.25Ga0.75N/GaN high mobility
heterostructures on sapphire substrates grown by plasma-induced molecular b
eam epitaxy and metalorganic chemical vapor deposition (MOCVD). The electri
cal transport properties of the two-dimensional electron gas in the AlGaN/G
aN heterostructures were investigated by a combination of capacitance-volta
ge profiling and Hall effect measurements. The performance degradation of t
he heterostructures is attributed to the reduction of the carrier density a
nd mobility due to ion bombardment, which is causing a creation of surface
and deep acceptor states. After rapid thermal annealing (RTA) at temperatur
es between 400 degrees C and 800 degrees C, the electrical properties of th
e heterostructures exposed at moderated plasma power density and bias were
mostly recovered. However, samples exposed at high power density lost the s
ignificant part of the electron sheet carrier concentration unrecoverable e
ven after RTA at 800 degrees C. (C) 2000 Elsevier Science Ltd. All rights r
eserved.