Effect of alumina thickness on Al_2O_3/InP interface with post deposition annealing in oxygen ambient

In this paper, the effect of alumina thickness on Al2O3/InP interface with post deposition annealing （PDA） in the oxygen ambient is studied. Atomic layer deposited （ALD） Al2O3 films with four different thickness values （5 nm, 7 nm, 9 nm, 11 rim） are deposited on InP substrates. The capacitance-voltage （C-V） measurement shows a negative correlation between the alumina thickness and the frequency dispersion. The X-ray photoelectronspectroscopy （XPS） data present significant growth of indium-phosphorus oxide near the Al2O3/InP interface, which indicates serious oxidation of InP during the oxygen annealing. The hysteresis curve shows an optimum thickness of 7 nm after PDA in an oxygen ambient at 500 ℃ for 10 min. It is demonstrated that both sides of the interface are impacted by oxygen during post deposition annealing. It is suggested that the final state of the interface is of reduced positively charged defects on Al2O3 side and oxidized InP, which degrades the interface.     

Kink effect in current–voltage characteristics of a GaN-based high electron mobility transistor with an AlGaN back barrier

The kink effect in current–voltage(IV)characteristic s seriously deteriorates the performance of a GaN-based HEMT.Based on a series of direct current(DC)IV measurements in a GaN-based HEMT with an AlGaN back barrier,a possible mechanism with electron-trapping and detrapping processes is proposed.Kink-related deep levels are activated by a high drain source voltage(Vds)and located in a GaN channel layer.Both electron trapping and detrapping processes are accomplished with the help of hot electrons from the channel by impact ionization.Moreover,the mechanism is verified by two other DC IV measurements and a model with an expression of the kink current.     

Kink effect in current-voltage characteristics of a GaN-based high electron mobility transistor with an AIGaN back barrier

The kink effect in current-voltage （IV） characteristic s seriously deteriorates the performance of a GaN-based HEMT. Based on a series of direct current （DC） IV measurements in a GaN-based HEMT with an AlGaN back barrier, a possible mechanism with electron-trapping and detrapping processes is proposed. Kink-related deep levels are activated by a high drain source voltage （Vds） and located in a GaN channel layer. Both electron trapping and detrapping processes are accomplished with the help of hot electrons from the channel by impact ionization. Moreover, the mechanism is verified by two other DC IV measurements and a model with an expression of the kink current.