Laser-Modified Chemical Beam Epitaxy of InGaAs/GaAs Multiple Quantum Wells Using Tris-Dimethylaminoarsenic
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H. K. DONG, N. Y. LI, and C. W. TU Department of Electrical and Computer Engineering, University of California at San Diego, La Jolla, California 92093-0407
ABSTRACT We report for the first time laser-modified chemical beam epitaxy (CBE) of InGaAs/GaAs multiple quantum well (MQW) structures using trimethylindium (TMIn), triethylgallium (TEGa), and tris-dimethylaminoarsenic (TDMAAs), a safer alternative to arsine. X-ray rocking curve (XRC) and low-temperature photoluminescence (PL) measurements were used to characterize the pseudomorphic strained quantum well structures. As determined by the X-ray simulation, laser irradiation during the InGaAs well growth was found to enhance the InGaAs growth rate and reduce the indium concentration in the substrate temperature range studied, 440-5000 C, where good interfaces can be achieved. We attribute these changes to laser-enhanced decomposition of TEGa and laser-enhanced desorption of TDMAAs. With laser irradiation, lateral variation of PL exciton peaks was observed, and the PL peaks became narrower.
INTRODUCTION In chemical beam epitaxy (CBE) and metalorganic chemical vapor deposition (MOCVD), laser-assisted growth has the potential for selective-area growth, doping, and change in composition for possible novel device applications[I-8]. Another issue of great interest is replacing the highly toxic and high-pressured AsH 3 with novel organometallic arsenic sources. There are mainly three requirements for the new precursors to be used in CBE, i.e., low but reasonable vapor pressure, low cracking temperature, and replacement of the As-H bond (which is believed to introduce the extremely toxic function) by other ligands. Trisdimethylaminoarsenic (TDMAAs, As[N(CH 3)2] 3), with As directly bonded to N, has been proposed as an alternative source to arsine[9-17]. Since there are no As-C and As-H direct bonds, TDMAAs is expected to have lower carbon incorporation and lower toxicity than AsH 3. TDMAAs has been successfully used in CBE or metalorganic molecular beam epitaxy (MOMBE) [9,10] and MOCVD [11,12] growth of GaAs. However, not much has been done in the epitaxial growth of other material systems using TDMAAs. Due to their potential applications in high-speed transistors [18] and optoelectronic devices [19], epitaxially grown InGaAs/GaAs pseudomorphic strained quantum well structures have been studied extensively. Previously, we have reported the CBE growth and characterization of InGaAs/GaAs multiple quantum wells (MQWs) using cracked (Tcrack= 30 0 °C) and uncracked TDMAAs[20]. In this paper, we report the study of Ar ion laser-modified CBE of InGaAs/GaAs MQWs using trimethylindium (TMIn), triethylgallium (TEGa), and TDMAAs.
597 Mat. Res. Soc. Symp. Proc. Vol. 354 01995 Materials Research Society
EXPERIMENTAL PROCEDURE
Experiments were performed in a modified Perkin Elmer 425B MBE system, equipped with gas lines for TMin, TEGa, and TDMAAs. An ultra high vacuum (UHV) was maintained by a turbomolecular pump, yielding a base pressure of 3.0x10- 9 Torr. TMIn and TEGa were int
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