Desorption of hydrogen from InN(0001¯) observed by HREELS

The kinetics of isothermal desorption of hydrogen from InN(0001¯) have been investigated using surface vibrational spectroscopy. Reductions in intensity of the N-H stretching and bending vibrations in high resolution electron energy loss spectra (HREELS) upon annealing indicated loss of surface hydrogen and was attributed to recombinative desorption. Hydrogen completely desorbs from the InN surface upon annealing for 900 s at 425 °C or upon annealing for 30 s at 500 °C. Surface hydrogen coverage was determined using the intensity of the N-H stretching vibrational loss peak. Fitting the coverage versus temperature for anneals of either 30 or 900 s indicated that the desorption was best described by second-order desorption kinetics with an activation energy and pre-exponential factor of 1.3 ± 0.2 eV and 10-7.3±1.0 cm2/s, respectively. In addition to thermal desorption, an increase in the carrier concentration in the film was also observed upon annealing to 450 °C or higher as shown in HREELS by a shift of the conduction band plasmon excitation to higher energy.