Trap characterization in AlGaN/GaN HEMT by analyzing frequency dispersion in capacitance and conductance

Abstract

AbstractAn analysis of frequency dispersion in capacitance and conductance of gate‐source contact of AlGaN/GaN HEMT was performed. Capacitance and conductance were measured at temperatures varying from 83 K to 370 K with bias voltage maintained at 0 V. In order to characterize trap states the conductance method was used considering series resistance. Hence, the parallel conductance Gp and capacitance Cp were calculated, and consequently interface trap density Dit and time constant t are deduced. The analysis is performed assuming a continuum of levels yielding to a trap density of approximately 10+12 cm−2eV−1 and a time constant varying between 1 µs and 3 ms. Activation energies and capture cross sections of three trap levels were deduced and their values were respectively (ΔEa1 = 0.201 eV, σn1 = 4.992 × 10−18 cm2), (ΔEa2 = 0.053 eV, σn2 = 2.585 × 10−21 cm2), (ΔEa3 = 0.121 eV, σn3 = 1.256 × 10−20 cm2). An electrical model was established with two levels of traps at AlGaN/GaN interface and one level located in barrier AlGaN surface. Copyright © 2010 John Wiley & Sons, Ltd.