Identification of the VAl-ON defect complex in AlN single crystals

In this Rapid Communication, we report positron annihilation results on in-grown and proton irradiation-induced vacancies and their decoration in aluminium nitride (AlN) single crystals. By combining positron lifetime and coincidence Doppler measurements with ab initio calculations, we identify in-grown VAl−ON complexes in the concentration range 10 exp 18 cm exp −3 as the dominant form of VAl in the AlN single crystals, while isolated VAl were introduced by irradiation. Further, we identify the UV absorption feature at around 360 nm that involves VAl.Peer reviewe

НОВЫЕ НАПРАВЛЕНИЯ РАЗВИТИЯ ТЕХНОЛОГИИ ПРОИЗВОДСТВА УЛЬТРАФИОЛЕТОВЫХ СВЕТОДИОДОВ

The paper presents results of the development of ultraviolet light−emitting diodes based on GaN/AlGaN heterostructures grown on AlN substrates by chloride−hydride vapor phase epitaxy. The peak wavelengths are in the range of 360—365 nm with a spectral width of 10—13 nm; the output optical power of LED dies is 50 mW at 350 mA.Представлены результаты по созданию ультрафиолетовых светодиодов на основе гетеро-структур GaN/AlGaN, выращенных на подложках AlN методом хлоридно-гидридной эпитаксии. Пиковые длины волн находятся в диапазоне 360—365 нм, ширина спектральной кривой составляет 10—13 нм, выходная оптическая мощность чипов светодиодов — 50 мВт при токе 350 мА

Publication IV Characterization of bulk AlN crystals with positron annihilation spectroscopy Characterization of bulk AlN crystals with positron annihilation spectroscopy

a b s t r a c t We have applied positron annihilation spectroscopy to study in-grown vacancy defects in bulk aluminium nitride (AlN) crystals grown by physical vapor transport. We interpret the lowest lifetime value of about 155 ps, measured at low temperatures, to represent the annihilations from the free state of the positron in the crystal lattice. The increased lifetime at high temperatures is an indication of positrons annihilating as trapped at vacancy defects, and a second lifetime component could be separated from the lifetime spectra at temperatures above 400 K. The same lifetime component non-open volume defects acting as shallow hydrogenic traps for positrons were detected, with concentrations of about 10 18 cm À3 or higher. These defects are the dominant negative acceptor defects in these samples