Group III nitride-based UV light emitting devices

Abstract

The effect of the non-radiative recombination center at or around the dislocations on the performance of the AlGaN-based UV light emitting diode (LED) is discussed. For high-efficiency emission, it is necessary to reduce the density of dislocations to less than 5 × 10 7 cm −2 .

Nearly stress-free substrates for GaN homoepitaxy

“…the luminescence yield of AlGaN-based UV-LEDs [10]. Such a low dislocation density can be achieved by homoepitaxial growth of GaN on free-standing substrates as it has been demonstrated in the last years [11,12].…”

Enhancement in emission angle of the blue LED chip fabricated on lens patterned sapphire (0 0 0 1)

“…In spite of the presence of high density of TDs due to the carrier localization in InGaN, the blue LEDs exhibit relatively high internal quantum efficiency (g int ). But detail study shows that the light emission efficiency becomes more sensitive to the nonradiative recombination centers at the TDs when shortening the emission wavelength since there is much weaker carrier localization [5,6]. Thus reducing TDs is essential for high efficient and reliable optoelectronic and electronic nitridebased devices.…”

Study on threading dislocations blocking mechanism of GaN∕AlxGa1−xN superlattices

“…Dislocations, which may act as nonradiative centers, are proved to have been a more serious problem in AlGaN / GaN light-emitting devices than in the corresponding longer wavelength InGaN / GaN devices. 6,7 One effective method to solve these problems is to use short-period GaN / AlGaN superlattices ͑SLs͒ as interlayers which was suggested and realized by Nakamura et al 8,9 The structure of SLs could not only relieve tensile strain between AlGaN layers and the underlying GaN but also block part threading dislocations ͑TDs͒ from penetrating into the subsequent layers. 4 The strain and stress relaxation process in SLs has been widely studied by experiments and calculations.…”