Green electroluminescence in GaP diodes and its correlation with cathodoluminescence measurements

Abstract

The results of a programme of research on green-emitting epitaxial diodes are reported. Diode quantum efficiencies of 0·07% DC and 0·40% pulsed have been obtained from an optimized structure. Room-temperature cathodoluminescence measurements on the bulk regions of device structures are correlated with diode performance. Major correlations are found in luminescence efficiency, light output characteristics and spectral distribution; the last is analysed in some detail to elucidate the room-temperature luminescence mechanisms. These results, coupled with the results of attempts to change the minority carrier injection ratio in the structure and the analysis of diode characteristics, have enabled the operation of our diodes to be understood in terms of abrupt junction theory.

Oxygen Gettering in Green GaP : N LED's Grown by Overcompensated LPE

“…The emitted radiation is primarily due to free exciton recombination with a peak emission at 2.24 eV (554 rim) (8,(33)(34)(35). Ga melts doped in excess of 1.9 • 10 -4 atomic fraction of A1 no longer exhibit the normal spectral features of GaP:N. A spectrum of an Al-gettered run (307-1) which was not intentionally doped with N is included for comparison.…”

“…Luminescence from the isoelectronic nitrogen center in GaP has been the subject of considerable study (1,2). Over the years it has been demonstrated that high efficiency green electroluminescence (EL) in GaP: N can be achieved by double liquid phase epitaxy (LPE) (3)(4)(5)(6)(7)(8) and vapor phase epitaxy (VPE) (9). The commonly employed acceptor impurity in the p-layer has been Zn, whereas either Te or S has been used as the donor impurity in the n-layer.…”

Determination of the Internal Quantum Yield and of the Injection Efficiency of Bed-Light Emitting (Al, Ga)As-DHS Diodes

“…The injection efficiency ratio for electrons and hoIes of green-light emitting GaP-TXD's was found with cathodoluminescence methods by Wight et al [6] and by additional measurements of the temperature dependence of the injection and cathodo-~-__ LinnCstr. 5 , DDR-7010 Leipzig, GDR.…”

“…s, L (oc) Sf which follows from (5) and (6). However, the measurements of AS' : (OC) a n d Sf are not possible immediately, because these signals occur a t the same photon energy.…”

“…In the present work the absorption coefficient ih found in the follou-ing manner: The signals 8; (see(6)) were measured on two diodes, which have nearly the same chemical compositions but different thicknesses of the AL. equal for both diodes, and indicating both diodes by the indices 1 and 6, we can deduce the following relation :…”