Growth Process of Si and GaAs in the Heterostructure GaAs/Si/GaAs(100).
- PDF / 368,325 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 0 Downloads / 295 Views
GROWTH PROCESS OF Si AND GaAs IN THE HETEH(SMUCTURE GaAs/Si/GaAs(100). M. LOPEZ,- Y. TAKANO, K. PAK, AND H. YONEZU Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Tempaku-cho, Toyohashi, Aichi 441, Japan. ABSTRACT The growth mode of Si on GaAs(l00) substrates and that of GaAs on very thin (1/4 - 3 ML) Si films grown pseudomorphically on GaAs was investigated by observing the behavior of the reflection-high energy electron diffraction (RHEED) specular spot intensity. From the presence of RHEED oscillations during the initial stage of the growth of Si on CGAs we infer a two-dimensional growth with nucleation on the terraces up to a thickness of 3 ML. During the posterior growth of GaAs on the seudomorphic Si films, a tendency towards three dimensional growth was observed. This tendency increased with the Si interlayer thickness. The causes of the formation of these islands are discussed. INIRODJCTION The heterostructure GaAs/Si/GaAs has, depending on the Si interlayer thickness, several applications. For Si interlayer with thickness t.• _ lML the 6"-doping is obtained which has applications in high electron mobility transistors and low resistance ohmic contacts [1]. Si films with thickness 2 ML _ tsi < 3 ML have been used as dislocation-blocking interlayers in the GaAs on Si heteroepitaxy. Hlashimoto et al reported a reduction of the dislolocation density by 2-3 orders of magnitude using these kind of Si interlayers [2]. GaAs/Si/GaAs heterostructures with 15 A thick Si films have been used in ultra-high-speed metal-semiconductors-metal photodetectors [3]. On the other hand, from a basic point of view, the GaAs/Si/GaAs structure can be used to obtain valuable information of the GaAs-Si interface formation, which is not possible to obtain in the growth of GaAs on conventional Si substrates. For example; Adomi et al [4,5], have recently studied the antiphase domains (APD's) formation in the growth of GaAs on Si films with double domain surface structure and with thickness 4 ML < ts, 5 6 ML. In this work, first we show by reflection-high energy electron diffraction intensity oscillations, that Si films with 1 x 2 single domain surface can be grown pseudomorphically on GaAs(l0O) substrates up to a thickness of 3 ML. Then, we studied the growth of GaAs on these Si films, free of the APD and lattice mismatch problems. The growth mode of GaAs by molecular beam epitaxy (MBE) and by migration-enhanced epitaxy (MEE) [61, was investigated observing the RHEED intensity behavior. EXPERIMENTAL
The GaAs(100) substrates were degreased and etched in
4:1:1 H2S0 4 :H2 0 2 :1' 2 t-
for 2 min at room temperature. They were mounted op a molybdenum block with indium and loaded into the MBE chamber. The samples were heated at 620"C to remove the thin oxide film. Then a 500 A GaAs buffer layer was grown at 580"C, with Ga and As4 beam flux intensities of 1.5 x 10-' and 5 x 10' Torr respectively. The Si growth was performed using an electron gun with a growth rate of 0.01 ML/s. RHEED patterns along th
Data Loading...
