Characteristics of MOCVD-Grown AlGaAs/GaAs SQW LASERS and GaAs MESFETs Fabrication on Si Substrate with SiO 2 -Back Coat
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CHARACTERISTICS OF MOCVD-GROWN AlGaAs/GaAs SQW LASERS AND GaAs FABRICATION ON Si SUBSTRATE WITH SiO2 -BACK COATING TAKASHI EGAWA, HITOSHI TADA, YASUFUMI KOBAYASHI, SHINJI TAKASHI JIMBO AND MASAYOSHI UMENO Department of Electrical and Computer Engineering, Technology, Gokiso-cho, Showa-ku, Nagoya 466, JAPAN *Intel Corporation, Santa Clara, CA 95052
NOZAKI*, Nagoya
MESFETs
TETSUO SOGA, Institute
ABSTRACT We discuss room temperature CW operation of AlGaAs/GaAs SQW lasers and GaAs MESFETs with good pinch-off characteristic on Si0 2 -back coated Si. The all-MOCVD-grown ,QW lpser on Si with thermal-cycle annealing, which has the EPD oý 1.5 x 10 cm- , has the threshold current as low as 55 mA (1.41 kA/cm ) under CW operation at room temperature. The pinch-off and the sidegating effect characteristics of GaAs MESFETs on Si have been improved by using Si0 2 -back coating of Si and higher growth temperature. The maximum transconductance of 160 mS/mm has been obtained for the MESFET with a 2.5 x 15 pm gate. The main origin of sidegating effect associates with the channel layer-undoped GaAs layer beneath it interface. The Si0 2 -back coating is found effective to obtain a lower background electron concentration in undoped GaAs layer and to control doping of the active layer in GaAs/Si.
INTRODUCTION Although the main problems with GaAs/Si, mismatches of lattice parameters and thermal expansion coefficients between GaAs and Si, and enhanced Si incorporation into GaAs layer still remain, laser diodes, solar cells, metal-semiconductor field-effect transistors (MESFETs) and high electron mobility transistors (HEMTs) have been fabricated on GaAs/Si grown by molecular beam epitaxy (MBE) or metalorganic chemical vapor deposition (MOCVD) technique [1-51. The mismatches of the lattice constants and the thermal expansion coefficients cause a high density of misfit and threading dislocations, and a large tensile strain in the GaAs layer. The threading dislocations in the active region of devices can act as non-radiative recombination centers and degrade device performance, particularly for minority carrier devices. These threading dislocations degrade device performance, such as threshold current and device lifetime. Most roomtemperature continuous-wave (CW) operating lasers on Si have been fabricated with the structure grown by combination of MBE and MOCVD techniques [2]. The unintentional or background doping in MOCVD-grown GaAs/Si influences the pinch-off characteristics of MOCVD-grown GaAs MESFETs and HEMTs [6]. To solve this problem some [4] used vanadium-doped GaAs buffer layers, which provides semi-insulating undoped GaAs on Si. However, most MESFETs on Si by MOCVD still have a pinch-off problem. In this paper, we demonstrate room temperature CW operation of all-MOCVD-grown AlGaAs/GaAs single quantum well (SQW) lasers and good pinch-off characteristics of GaAs MESFETs on Si with Si0 2 -back coating. We also discuss suppression of the Si autodoping in the GaAs/Si and the sidegating effect of GaAs MESFETs on Si02 -back coated Si
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