Effect of Illumination on the Electrical Characteristics of AlGaN/GaN FETs

Abstract

Piezoelectric AlGaN/GaN FETs with high carrier mobility have been fabricated yielding I DS 450 mA/mm and g m 200 mS/mm. Upon turn-on of the device from the pinch-off state a significant delay in the drain current build-up is observed. This effect depends on the pinch-off time and the pinch-off voltage and can be removed by either a brief UV-illumination or a V DS b 25 V applied in on-state. The relaxation time t of this effect is of the order of several hundred seconds. From the temperature dependence of t an activation energy of about 280 meV and a capture cross section of 4X4 Â 10 À18 cm 2 can be extracted.

Sulfuric acid and hydrogen peroxide surface passivation effects on AlGaN/GaN high electron mobility transistors

“…[12][13][14] Note that there is a departure from the straight line at low temperatures. The reason for this is unclear but it may indicate the onset of the domination of states with much smaller activation energies.…”

“…For the untreated device, the activation energy is 0.33 eV, which is in good agreement with the low-bias Arrhenius plots of Figure 3 and the trap depths reported previously. [12][13][14] However, for the H 2 SO 4 treated device, the activation energy is very similar at low temperatures (0.3 eV) but increases significantly to 0.68 eV at high temperatures. This again highlights the fact that the H 2 SO 4 treatment has introduced some deep level traps in the surface states.…”