GaNAsBi Semiconductor Alloy with Temperature-Insensitive Bandgap
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GaNAsBi Semiconductor Alloy with Temperature-Insensitive Bandgap M. Yoshimoto, W. Huang1, G. Feng2, and K. Oe1 Cooperative Research Center, Kyoto Institute of Technology 1 Department of Electronics and Information Science, Kyoto Institute of Technology 2 Venture Laboratory, Kyoto Institute of Technology Sakyo, Kyoto, 606-8585, Japan ABSTRACT GaNy As1-x-yBix alloys were grown by molecular beam epitaxy (MBE) using solid Ga, Bi, and As sources and nitrogen radicals generated from N2 in rf plasma. To achieve Bi incorporation into the epilayer, As flux was adjusted in a limited range on the brink of As shortage on the growing surface. GaNy As1-x-yBix alloys lattice-matched to GaAs substrates with different photoluminescence (PL) peak energies were obtained. The GaNy As1-x-yBix alloy lattice-matched to GaAs turned out to have the structure of Ga(N0.34Bi0.66)zAs1-z. The PL spectra showed that the PL peak energy of GaNy As1-x-yBix alloy decreased with increasing Bi and N contents with redshift coefficients of ~62 meV/%Bi and ~130 meV/%N, respectively, at room temperature. The temperature dependence of the PL peak energy for GaNy As1-x-yBix in the temperature range of 150~300 K is much smaller than that of InGaAsP. The temperature coefficients of GaNy As1-x-yBix bandgaps were governed by the GaBi molar fraction and decrease with increasing GaBi molar fraction.
INTRODUCTION Semiconductor materials with a temperature-insensitive bandgap have been attracting intense attention, as they are expected to be used as an active layer to realize a laser whose lasing wavelength is maintained stable with the variation of ambient temperature [1]. For the conventional laser device using InGaAsP as an active layer, the lasing wavelength varies with the ambient temperature fluctuation, because the bandgap and refractive index of InGaAsP vary with the ambient temperature. The laser diode with the temperature-insensitive wavelength eliminates the needs for the use of a massive Peltier device for temperature control in the transmitter of a wavelength-division-multiplexing (WDM) optical fiber communication system. The realization of the transmitter without the Peltier device allows more widespread application of the WDM system. Bi-containing III-V alloys have been proposed as promising semiconductor materials with temperature-insensitive bandgaps [2]. Research focusing on Bi-containing III-V semiconductors has been going on for decades for applications for infrared devices. InSbBi [3], InAsBi [4], and InAsSbBi [4, 5] have been grown by various growth techniques. Although Bi belongs in the group V elements, InBi is not normally considered as III-V compounds since it crystallizes in a tetragonal structure and is a semimetal [6]. GaBi is considered to be nonexistent, and it is expected to show a semimetallic nature [7]. It has been shown that small amounts of InBi dissolve in InAs [4, 8] or GaBi dissolve in GaAs [9] to form alloys with the zinc-blende structure. Recently, successful creation of InGaAsBi has been reported [10]. Rene
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