Redshift ofA₁(longitudinal optical) mode for GaN crystals under strong electric field

Abstract

We investigated the property of GaN crystals under a strong electric field. The Raman spectra of GaN were measured using an ultraviolet laser, and a remarkable redshift of the A 1 (LO) mode was observed. The role of the surface depletion layer was discussed, and the interrelation between the electric field and phonons was revealed. First-principles calculations indicated that, in particular, the phonons that vibrate along the [0001] direction are strongly influenced by the electric field. This effect was confirmed by a surface photovoltage experiment. The results revealed the origin of the redshift and presented the phonon property of GaN under a strong electric field.

Investigation of the reverse recovery characteristics of vertical bulk GaN-based Schottky rectifiers

“…Meanwhile, it is also difficult to fabricate vertical devices in which current flows towards threading dislocations on such foreign substrates [9]. However, the recent research of free-standing GaN substrates with a low defect density (on the order of 10 6 cm −2 or less) has achieved great progress [6,[10][11][12] and attracted a renewed interest in the development of the homo-epitaxially growth of vertical-type electronic devices, such as the bulk GaN-based Schottky diode, which can be employed in power rectifier applications [13][14][15][16]. Compared to the p-n junction diode, the Schottky diode does not exhibit a minority carrier storage effect due to its unipolar nature, and thus shows a negligible reverse transient current and faster switching time.…”

Large Negative Thermal Quenching and Broadening Lineshape Analysis of Acceptor-Associated Yellow Luminescence in Si-Doped GaN

“…Figure a shows variable-temperature PL spectra of sample A1 under the excitation of quasi-continuous 370 nm laser pulses, and Figure b shows the variable-temperature PL spectra of sample A1 excited by the 325 nm continuous-wave laser. The penetration depth of 325 nm laser in GaN was 85–100 nm, , and the penetration depth of 370 nm laser could be greater than 100 nm due to its largely reduced optical absorption in GaN.…”