Abstracts for MRS Internet Journal of Nitride Semiconductor Research , Volume 3, Articles 24-31
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IMIRIS Internet
Nitride of Semiconductor Research
An electronic, peer-reviewed Journal pubiished by the Materials Research Society. http://nsr.mij.mrs.org/
Volume 3, Articles 24-31
Editors-in-Chief: CR. Abernathy, B. Monemar [email protected] http://nsr.mij.mrs.org/3/24/ Analysis of the Visible and UV Electroluminescence in Homojunction GaN LED's F. Calle1, E. Monroy1, F.J. Sänchez1, E. Murioz1, B. Beaumont2, S. Haffouz2, M. Leroux2, and P. Gibart2 1 CiudadUniversitaria 2 CRHEA-CNRS The electrical and electroluminescent properties of MOVPE GaN p-n homojunctions have been analyzed as a function of temperature and bias. Electroluminescence is observed for V>3 V under de and ac conditions. The main emission at low Tis a donor-aeeeptor transition involving shallow aeeeptors, though it disappears at higher 7" due to the ionization of the aeeeptors and compensation by ionized donors. Room temperature de and ac electroluminescence spectra evolve under increasing bias from a blue-shifting visible band involving deep states at the p-type side of the p-n junetion, to a band-to-band uv recombination at high bias. In agreement, the superlinear dependence of light-current characteristics at low current injeetion becomes linear when the defects are saturated. Time analysis of the spectra vs pulse duration and duty cycle allows the determination of the visible radiative recombination and relaxation times associated to the Mg-related deep states, which are found to behave as aeeeptors lying 0.55 eV above the valence band. A simple 3-level model is able to explain the visible emission, which involves the conduetion band (or shallow donor) and those deep aeeeptors in the p-layer. Optimum UV/visible ratio emis sion requires intense and relatively long pulses, with a high duty cycle to impede visible recombination. Order No. NS003-024 ©1998 MRS http://nsr.mij.mrs.org/3/25/ AMMONO Method of BN, AIN and GaN Synthesis and Crystal Growth R. Dwilinski1, R. DoradzinskPJ. Garczynski2, L. Sierzputowski2, M. Palczewska3, A. Wysmolek1, and M. Kaminska1 1 Warsaw University 2 Warsaw Institute of Technology Institute of Electronic Materials Technology Microcrystals of BN, AIN and GaN were obtained by the AMMONO method, in which nitridization of metal oecurs in supercritical ammonia, at relatively low temperature and pressure conditions (below 550°C and 5 kbar). The reaction rate was regulated by the amount of mineralizers, i.e. alkali metal amides. All crystals obtained by AMMONO method revealed intense and
MIJ-NSR Abstracts
• Journalmaster: E.S. Hellman [email protected]
homogenous luminescence. Significant improvement of the optical prop erties was observed for crystals grown in the presence of Rare Earth elements. For such GaN crystals, helium temperature photoluminescence spectra were dominated by near-band-gap recombination. Exciton lines were extremely narrow, with full-width half-maximum (FWHM) as low as 1 meV. The concentration of uncompensated shallow donors in AMMONO GaN determined by electron paramagnetic reso
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