Abstract
The n-type GaN epilayers with low electron density were developed on a native substrate using the metalorganic vapour phase epitaxy method and investigated under pulsed electric fields until material breakdown and optically in the spectrum range from 0.1 THz to 60 THz at two temperatures of 77 K and 300 K. The epilayers demonstrated the low-field electron mobility and density values reaching up to 1021 cm2/V·s and 1.06 × 1016 cm−3 (at 300 K) and 2652 cm2/V·s and 0.21 × 1016 cm−3 (at 77 K), respectively. Maximum injected electric power value till the damage of the GaN epilayer was found to be up to 1.8 GW/cm3 and 5.1 GW/cm3 at 77 K and 300 K, respectively. The results indicate new practical possibilities of the GaN material controlled by an external electric field.
Highlights
Academic Editors: Milan Ťapajna andThe high quality of gallium nitride (GaN) epilayers is crucial for the fabrication of high-power and high-frequency semiconductor devices [1–5]
The best parameters for such applications on a native substrate were obtained by pulsed sputtering deposition [1,12], molecular beam epitaxy [2,3,13], and metalorganic vapour phase epitaxy (MOVPE) [14] with the smallest values for electron density of 2 × 1016 cm−3, 9.2 × 1015 cm−3, and 9.9 × 1015 cm−3, respectively
The reason for such high electron mobility was the low density of threading dislocations (TDD) in the used substrates, the values of which were reported to be (2–4) × cm−3 [1,12,14], 4 × cm−3 [13], (0.5–5) × 109 cm−3 [3], and 2 × 106 –2 × 1010 cm−3 [2]
Summary
The high quality of gallium nitride (GaN) epilayers is crucial for the fabrication of high-power and high-frequency semiconductor devices [1–5]. The best parameters for such applications on a native substrate were obtained by pulsed sputtering deposition [1,12], molecular beam epitaxy [2,3,13], and metalorganic vapour phase epitaxy (MOVPE) [14] with the smallest values for electron density of 2 × 1016 cm−3 , 9.2 × 1015 cm−3 , and 9.9 × 1015 cm−3 , respectively Carrier mobility is another important parameter for the discussed structures, with the highest low-field mobility values at low temperatures reported to be 3470 cm2 /V·s, 2637 cm2 /V·s, and 6660 cm2 /V·s, respectively, while at room temperature it remained above 1000 cm2 /V·s in all cases. Our results demonstrate high low-field mobility and low density of electrons in studied epilayers, which can be used for the development of GaN-based devices for high-power and high-frequency applications
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