INTERDIFFUSION AND CONVERSION OF INP/IN0.53GA0.47 AS SUPERLATTICES INDUCED BY P-TYPE DOPANTS

Zn diffusion into an unstrained InP/In0.53Ga0. 47As superlattice has been observed to result in the formation, first, of a strained layer In1xGaP/In l- xGaAs supperlattice due to the selective diffusion of In and Ga, then a Zn3P2/In1-xGaxAs superlattice due to “kickont” of the cations, and finally a Zn3P2/Zn3As2superlattice. The lateral confinement of Zn induced interdiffusion and conversion is examined by diffusing through a 3 μm period Si3N4grating, The effects of Cd diffusion and Be ion implantation are also examined. Grganometallic chemical vapor deposited InP/In0. 53Gao.47 As superlattices were diffused at 600 or 650 oC in sealed ampoules with Zn3As2or Cd3P2powder as the dopant source. Samples were examined by secondary ion mass spectrometry and analytical electron microscopy. In the grating experiment, cation homogenization resulted in the formation of a uniform unconfmed strained layer superlattice with superior surface quality in the regions protected by Si3N4. Zn3P2superlattice conversion was confined within the grating window regions; however, a thick unconfmed Zn3P2layer was observed to form below the superlattice. A Ga concentration spike was present between this thick Zn3P2layer and the underlying substrate. Cd was less efficient at intermixing the superlattice, owing largely to its relatively low solubility and diffusion coefficient. Partial intermixing was induced by Be implantation, with Be segregation into the InP layers observed near the implant peak. © 1990, American Vacuum Society. All rights reserved.