Point defects in group III nitrides: A comparative first-principles study

Abstract

One of the main challenges in the development of wide bandgap semiconductor devices is to understand the behavior of defects and avoid their harm. Using density-functional theory calculations with hybrid functional, we systematically investigated the neutral and charged native point defects (vacancy, interstitial, and antisite defect) in GaN, AlN, and InN crystals in terms of local geometry relaxation, formation energies, and electronic and diffusion properties. By comparing the defect configuration and transition levels as a function of the Fermi level, we show that Ga interstitial (Gaoc, Gate) in GaN, N vacancy (VN), N interstitial (Ni), In antisite (InN), and In interstitial (Inte, Inoc) in InN can exist stably only in the positive charge states with donor level and VIn is stable in the neutral state, while the other defects exhibit both donor and acceptor behavior. Among them, the most stable defects are identified as VN for p-type nitrides and VGa, VAl for n-type nitrides. These results, providing a mechanism for self-compensation effects, explain the reduced doping efficiencies for both n-type and p-type nitrides due to defects. Moreover, it is also demonstrated that N interstitial diffuses faster than vacancy, which are mainly responsible for the low concentration of N interstitials and N-based defect complexes produced in nitrides. Significantly, the trends of formation energy, transition level, and migration barrier of nitrides are also consistent with their intrinsic atomic size and bandgap. Our study is important for the identification and control of point defects in nitrides, which have a profound impact on device performance and reliability.

Dynamics Studies of Nitrogen Interstitial in GaN from Ab Initio Calculations

“…The data in Table 2 indicates that the rotation and migration barriers vary in the different charge states and part of our results are consistent well with previous work [ 14 , 18 , 19 ]. The results show that the differences between the upward and downward paths in plane are due to the rotation barrier.…”

“…This configuration is a N-N dimer tilted bond as presented in Figure 2 , and the calculated formation energy of the neutral state is 4.67 eV. These findings correspond to the previous researches [ 12 , 14 , 17 ] well. Furthermore, some new specific characteristics of these N i were concluded, and they could be directly applied in later simulations or experiments.…”

“…As an important complementarity, theoretical simulation is another efficient approach to understanding the property of defects. Among the theoretical work on GaN, varieties of studies [ 12 , 13 , 14 , 15 , 16 , 17 ] were put forward to obtain the transition levels related to the defects. They eventually concluded that N i can occupy five charge states within the band gap.…”

Temperature dependence of elastic strain and damage build-up in He implanted AlN

“…AlN indeed suggest that vacancy migration occurs around 1000°C [30], which agrees well with recent calculations giving a migration energy of the nitrogen vacancy of 3,37 eV [5], corresponding to the VN annealing temperature of about 1000°C by using the Harmonic Transition State Theory [54]. Our results thus suggest an increased mobility of interstitial-type defects at 550°C compared to RT.…”

“…Group III-nitrides and their alloys have gained great interest as direct band gap semiconductors with outstanding properties making them ideally suited for electronic and optoelectronic devices, in particular light emitting diodes [1][2][3]. They are increasingly used in power electronics and high electron mobility transistors (HEMTs) [4] and are potential candidates for high-temperature, high-power, highfrequency, and short-wavelength electronics under radiation environments in space [5][6]. Their known resistance to radiation-induced amorphisation [7] also makes them suitable as insulating and optical materials to be used in future fusion reactors in a variety of applications among which diagnostic systems.…”