Liquid phase epitaxial growth of InGaAs on InP using rare-earth-treated melts

Abstract

High-quality In0.53Ga0.47As epilayers have been grown on semi-insulating (100) Fe-doped InP substrates. The growths were performed by liquid phase epitaxy (LPE) using rare-earth-doped melts in a graphite boat. The rare-earth elements studied were Yb, Gd and Er which act as gettering agents of impurities. Hall measurements show an elevated electron mobility for rare-earth-treated samples over undoped samples, μe=11 470 cm2/V s at 300 K and reduced carrier concentration (n-type), 9.33×1013 cm−3. The Hall results indicate an improvement in layer quality, but suggests that the treated layers are compensated. Photoluminescence (PL) studies show that the layers grown from rare-earth-doped melts have higher integrated PL efficiency with narrower PL linewidths than the undoped melt growths. The grown materials were fully characterized by Fourier transform infrared spectroscopy, double-crystal x-ray diffraction, energy dispersive spectroscopy, secondary-ion-mass spectroscopy, and deep level transient spectroscopy (DLTS). Compositional measurements reveal no measurable incorporation of rare-earth elements 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-earth elements. Subsequent glow discharge mass spectrometry measurements reveal many impurities within the rare-earth elements which preferentially might lead to p-type doping centers and/or deep levels. Thus, rare-earth doping of LPE melts clearly improves epitaxial layer quality, however, the purity of commercially available rare-earth elements hinders optimal results.