Lattice-matched In 0.49 Ga 0.51 P/GaAs superlattices were grown on (001) GaAs substrates using metalorganic chemical vapor deposition. The interface properties were characterized by photoluminescence, transmission electron microscopy, and x-ray diffraction. By varying the growth temperature, the precursor flow rates, and the growth interruption at the interfaces, we found that, while arsenic and phosphorus carry over have some effect on the formation of a lowbandgap InGaAsP quaternary layer at the interfaces, the In surface segregation seems to play an important role in the formation of the interface quaternary layer. Evidence of this indium segregation comes from x-ray and photoluminescence studies of samples grown at different temperatures. These studies show that the formation of an interfacial layer is more prominent when the growth temperature is higher. Growing a thin (;1 monolayer thick) GaP intentional interfacial layer on top of the InGaP before the growth of the GaAs layer at the P!As transition effectively suppresses the formation of the low-bandgap unintentional interface layer. On the other hand, the growth of a thin GaAsP (or GaP) layer before the growth of the InGaP layer, at the As!P transition increases the formation of a low-bandgap interfacial layer. This nonequivalent effect of a GaP layer at the two interfaces on the PL properties is discussed.

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Data are presented on the insulating properties and capacitance-voltage (CV) characteristics of metal-oxide-semiconductor (MOS) device-thickness (below ~100 nm) native oxides formed by wet thermal oxidation of thin InAlP epilayers lattice matched to GaAs. Low leakage current densities of J=1.4 x 10 -9 A/cm 2 and J=8.7 x 10 -11 A/cm 2 are observed at an applied field of 1 MV/cm for MOS capacitors fabricated with 17 nm and 48 nm oxides, respectively. TEM images show that the In-rich interfacial particles which exist in 110 nm oxides are absent in 17 nm oxide films. Quasi-static capacitance-voltage measurements of MOS capacitors fabricated on both n-type and p-type GaAs show that the InAlP oxide-GaAs interface is sufficiently free of traps to 1 support inversion, indicating an unpinned Fermi level. These data suggest that InAlP native oxides may be a viable insulator for GaAs MOS device applications. 2Due to the wide array of high electron mobility alloys of varying bandgaps that can be epitaxially grown on its surface, GaAs remains the most widely used semiconductor for high-speed electronic applications. While Schottky gates are commonly used in high-speed GaAs transistors, the restricted forward bias (a few tenths of a volt) that can be applied without excessive gate leakage currents limits their power handling capability.The electrical characteristics of native oxides of GaAs are far inferior to those of SiO 2 on Si, and an alternative insulator has long been pursued 1,2 to enable the preferred metal-insulator-semiconductor gate structure. Many deposited insulator/GaAs structures have been investigated, although only a few have yielded promising results. 3-6 Native oxide films on GaAs can offer advantages of processing convenience and low cost.Wet thermal oxides of AlGaAs 7 have been studied but found to suffer from midgap traps caused by residual interfacial As. 8 These traps lead to increased interface recombination velocity 9,10 and high leakage currents. 11 However, the wet thermal oxides of As-free As shown in the bright-field TEM images of Fig. 2, dark particles exist near the oxide/GaAs interface in the 110 nm oxide of Fig. 2 (a), while no dark interfacial particles appear in the 17 nm oxide of Fig. 2 (b). Fig. 2 (b) is representative of the entire observable area for this and a second wedge-polished cross section specimen, with the absence of particles also confirmed for plan-view specimens (not shown) in which possible loss of particles due to ion milling and electron beam interactions is suppressed by the fact that they are protected from the vacuum by the substrate and overlying oxide film. The interfacial particles in Fig. 2 (a) are believed to be indium rich based on Z-contrast TEM images 16 (not shown) and Auger depth profiling. 17 The size of the particles increases with the progressive consumption of the InAlP epilayer during oxidation. 16 We hypothesize that In, the heaviest element in the structure, outdiffuses more slowly than the other alloy constituents and hence accumulates near the inter...

In As ∕ Ga Sb type-II superlattices (SLs) were grown on (001) GaSb substrates by metal organic chemical vapor deposition. Besides the expected tensile stress introduced by the InAs layers in the SLs, additional tensile stress is found in the InAs∕GaSb SLs from the simulation of x-ray diffraction (XRD) curves of the SLs. High-resolution transmission electron microscopy and XRD of the SLs grown with different interface gas switching procedures suggest that the additional tensile stress is mainly located at the GaSb→InAs interface. To compensate for the tensile stress in the SL structures, we show that introducing ∼2-ML-thick InAs0.8Sb0.2 layer at the interfaces of the SL improves the morphology and the structural properties of the SLs significantly.

Data are presented demonstrating continuous wave laser operation at −185°C of an InP–InAlGaAs–InAlAs double heterojunction bipolar transistor with strained InGaAs quantum wells incorporated in the p-type base region. The laser exhibits a peak wavelength λ∼1544nm when biased in the forward active mode in the common-emitter configuration. A threshold current IB=10mA is observed.