Effects of electrical stress on the characteristics and defect behaviors in GaN-based near-ultraviolet light emitting diodes

Abstract

The degradation mechanism of GaN-based Near-ultraviolet (NUV, 320-400 nm) light emitting diodes (LEDs) with low-indium content under electrical stress was studied from the aspect of the defect. A decrease of the optical power, and an increase of the leakage current were observed after electrical stress. The defect behaviors were characterized using deep level transient spectroscopy (DLTS) measurement under different filling pulse widths. After stress, a defect with the energy level of 0.47-0.56 eV increases, accompanied by a decrease of 0.72-0.84 eV defect. Combing the defect energy level with the increased yellow luminescence in photoluminescence spectral, the device degradation can be attributed to the activation of the gallium vacancy and oxygen related complex defect along dislocation, which was previously passivated with hydrogen. This study reveals the evolution process of defects in the time dimension under electrical stress and their spatial location, laying a foundation for the manufacture of GaN-based NUV LEDs with high reliability.

Effects of Mg-doping temperature on the structural and electrical properties of nonpolar a-plane p-type GaN films

“…III-nitrides are promising semiconductor systems with widespread applications for power, [1,2] radio frequency (RF), [3,4] optoelectronic, [5,6] and light-emitting devices. [7,8] In general, most of the conventional III-nitride-based devices are epitaxially grown along the c-plane direction. However, a strong built-in electric field parallel to the c-direction induced by the spontaneous and piezoelectric polarization forces the spatial separation of electrons and holes in the quantum wells, causing a reduction of the recombination rate and a redshift of the emission wavelength in III-nitrides based lightemitting devices.…”