LIQUID-PHASE EPITAXIAL-GROWTH OF INGAAS ON INP USING RARE-EARTH-TREATED MELTS

High-quality In(0.53)Ga(0.47)AS epilayers have been grown on semi-insu lating (100) Fe-doped InP substrates. The growths were performed by li quid phase epitaxy !LPE) using rare-earth-doped melts in a graphite bo at. The rare-earth elements studied were Yb, Gd and Er which act as ge ttering agents of impurities. Hall measurements show an elevated elect ron mobility for rare-earth-treated samples over undoped samples, mu(e )=11 470 cm(2)/V s at 300 K and reduced carrier concentration (n-type, 9.33x10(13) cm(-3). The Hall results indicate an improvement in layer quality, but suggests that the treated layers are compensated. Photol uminescence (PL) studies show that the layers grown from rare-earth-do ped melts have higher integrated PL efficiency with narrower PL linewi dths than the undoped melt growths. The grown materials were fully cha racterized by Fourier transform infrared spectroscopy, double-crystal x-ray diffraction, energy dispersive spectroscopy, secondary-ion-mass spectroscopy, and deep level transient spectroscopy (DLTS), Compositio nal measurements reveal no measurable incorporation of rare-earth elem ents into the grown epilayers. DLTS measurements indicate the creation of two deep levels with rare-earth treatment. which is attributed to either the rare earth elements or impurities from within the rare-eart h elements. Subsequent glow discharge mass spectrometry measurements r eveal many impurities within the rare-earth elements which preferentia lly might lead to p-type doping centers and/or deep levels, Thus, rare -earth doping of LPE melts clearly improves epitaxial layer quality, h owever, the purity of commercially available rare-earth elements hinde rs optimal results. (C) 1996 American Institute of Physics.