Molecular beam epitaxial growth and device performance of metamorphic high electron mobility transistor structures fabricated on GaAs substrates

Abstract

Single and double pulse doped metamorphic high electron mobility transistor (MHEMT) structures have been grown on GaAs substrates by molecular beam epitaxy. A linear indium graded buffer layer was used to expand the lattice constant. Transmission electron microscopy cross sections showed planar interfaces. Threading dislocations were not observed along both cleavage directions. For a single pulse doped MHEMT structure with an In0.56Ga0.44As channel layer, the mobilities (10 030 cm2/V s at 292 K; 32 560 cm2/V s at 77 K) and sheet density (3.2×1012 cm−2) were nearly equivalent to values obtained for the same structure grown on an InP substrate. Secondary ion mass spectroscopy measurements of a double pulse doped structure indicated no measurable migration of the silicon doping pulses. MHEMT devices with 0.15 μm gates were fabricated, tested, and compared to GaAs pseudomorphic HEMT devices of the same geometries. Above 9 GHz, the MHEMT devices exhibited lower noise figure. From 3 to 26 GHz, the associated gain was 3 dB higher with the MHEMT devices. Also higher linearity performance was obtained with the MHEMT devices. At 4 GHz MHEMT linearity measurements yielded third order intermodulation distortion intercepts, IP3, of 36–39 dBm with linearity figure of merits of 60–90. Due to the significantly lower cost and more robustness of GaAs substrates compared to InP substrates, MHEMT technology is very promising for low cost manufacturing of low noise amplifiers.

Thermal characteristics of InP, InAlAs, and AlGaAsSb metamorphic buffer layers used in In0.52Al0.48As/In0.53Ga0.47As heterojunction bipolar transistors grown on GaAs substrates

“…Surface roughness and thermal conductivity data are shown in Table II. We observe larger surface roughness than other reported work 5,6 and are presently adjusting our growth conditions to reduce roughness. Buffer-layer thermal conductivities were determined by measuring the thermal impedance of 1 m ϫ 100 m Pt conductors of 50-nm thickness.…”

Photoluminescence from GaInP layers and GaInP/AlGaInP quantum wells grown by molecular beam epitaxy with varying growth temperature, phosphorus gas pressure, and substrate orientation

“…Interestingly, PL from the 10 -[1 1 1]A being weakly affected by temperature variations between 505 C and 523 C is strongly affected by pressure variations when Po1 Â 10 À7 mbar. A rapid reduction in intensity is likely due to impurity-related defects created especially in the 10 -[1 1 1]A sample during nucleation [13,14]. We prove later that the terraced 10 -[1 1 1]A with an increased sticking probability relative to the nominally flat (1 0 0)-0 surface is very sensitive to atomic oxygen.…”

As–P interface-sensitive GaInP/GaAs structures grown in a production MBE system

“…A light delta-doping plane (2 Â 10 12 cm À2 ) limits parallel conduction in the delta-doping plane and avoids the filling of the second energy level of the channel. The low-conduction band offset in the case of GaInP/GaAs HEMT (less than 0.15 eV) [6] enables the wave function to be located near the interface and to penetrate into the barrier (Fig. 1).…”