Pure Green Light-Emitting Diodes Based on High Quality ZnTe Substrates and a Thermal Diffusion Process

Kenji SATO  Mikio HANAFUSA  Akira NODA  Atsutoshi ARAKAWA  Toshiaki ASAHI  Masayuki UCHIDA  Osamu ODA  

IEICE TRANSACTIONS on Electronics   Vol.E83-C   No.4   pp.579-584
Publication Date: 2000/04/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Blue Laser Diodes and Related Devices/Technologies)
ZnTe,  VGF,  green LED,  thermal diffusion,  

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Pure green ZnTe light-emitting diodes (LEDs) were first realized reproducibly based on high quality ZnTe substrates and a simple thermal diffusion process. This success which overcomes the compensation effect in II-VI materials is due to the use of high quality p-type ZnTe single crystals with low dislocation densities of the level of 2000 cm-2 grown by the vertical gradient freezing (VGF) method and the suppression of as compensating point defects by low temperature annealing with covering the surface of the substrates by the deposition of n-type dopant, Al. The thermal diffusion coefficient and the activation energy of Al were determined from the pn interface observed by scanning electron spectroscopy (SEM). The formation of the intrinsic pn junctions was confirmed from the electron-beam induced current (EBIC) observation and I-V measurement. The bright 550 nm electroluminescence (EL) from these pn-junctions was reproducibly observed under room light at room temperature, with the lifetime exceeding 1000 hrs.