The collector multiplication in InP/Ga0.47In0.53As heterojunction bipolar transistors was found to increase with temperature, and to have a weak electric field dependence. This anomalous behavior has a profound impact on device characteristics.

We demonstrate the first long-wavelength quantum well infrared detector using the lattice-matched In0.53Ga0.47As/InP materials system. The responsivity has been found to be larger than that for similar GaAs/AlxGa1−xAs detectors.

We have investigated the effects of ion bombardment on the electrical properties of intentionally doped InP and InGaAs grown by metalorganic molecular-beam epitaxy. The sheet resistivity and mobility of n+InP (Sn) and n+InGaAs (Sn) or p+InGaAs (Be) epilayers grown on semi-insulating InP substrates were measured as a function of ion species (O, B, H, or Fe), ion dose (1012–1015 cm−2), and post-implant annealing temperature (100–600 °C). In n+InP, the resistivity after bombardment goes through a maximum with annealing temperature, reaching a value of ∼106 Ω/⧠ for 0.5-μm-thick films after implantation with H or O and annealing at 200–300 °C. The as-grown resistivity is restored by annealing above 500 °C. Ion doses below 1012 cm−2 actually lead to a decrease in resistivity through the creation of shallow donor levels. By contrast, the implantation of Fe above a critical dose where the Fe density exceeds the dopant concentration leads to the formation of thermally stable, high-resistivity (>106 Ω/⧠) material. The temperature dependence of the resistivity shows an activation energy of 0.67 eV, which corresponds to the acceptor level of substitutional Fe in InP. Both n+InGaAs and p+InGaAs show somewhat similar behavior after implantation with maximum resistivities of ∼105 Ω/⧠ regardless of implant species. Once again for relatively low doses of O or H (below ∼1013 cm−2 in this case) there is creation of shallow defect levels that lower the resistivity of the material. The formation of these levels in InP has been investigated in more detail by measuring the depth-dependent carrier profile in implanted high-resistivity InP. The profile of the damage-induced centers is in close correlation with the nuclear energy deposition profile of the implanted ion in some cases, and with the profiles of stoichiometric excess due to unequal recoil of the lattice constituents in other cases.

Surface roughening of (100) InP films grown by metalorganic molecular beam epitaxy was observed by scanning force microscopy. The roughening process gives rise to periodic elongated terraces aligned in the [OTl] direction; kinetic control by surface diflfusion activation is indicated by the dependence on group III and V fluxes, and growth temperature. Below a given temperature for each set of growth parameters the surface roughness shows two distinct power law regimes dependent on the film thickness. This result supports growth models using ballistic aggregation and surface diffusion.PACS numbers: 68.55. Bd, 61.16.Ch, 68.35.Bs To achieve abrupt and planar interfaces in semiconductor structures grown by molecular beam epitaxy (MBE) techniques, it is important to examine the growth morphology and correlate it to the growth mechanism. This mechanism usually depends on surface diffusion of atoms to kink sites, which are energetically more favorable to nucleation. The morphology of the epitaxial film is then influenced by deposition rate, which controls the adatom population on the surface, and substrate temperature, which affects the surface diffusion rate of the species. There are thus different forms of kinetic roughening, depending on the relative magnitude of these variables. In particular, at low temperatures, the reduced surface mobility can lead to three-dimensional growth, where islands nucleate on incomplete monolayers. Recently, there has been considerable theoretical interest in surface roughness and growing interfaces. In particular, scaling behavior of the interface width-or surface roughness, W = [<(/z -(A>)^>] *^^, where h is the film thickness-is observed in these models. The scaling is expected to be of the form lPr(L,/)-Ly(//L°/^),where f{x)--x^ for x«Cl and /(jc)^ const for x^l, for a system with size L and time t [1,2]. Different models of growing interfaces have been proposed [2-4] and, although the values for a and p agree for spatial dimension rf = 2 (substrate dimension rf-1), for d>l this is not true [1]. Until now, power law scaling of surface roughness in MBE has been observed experimentally only in the case of iron films grown by this technique [5].Several experiments have been performed to understand the processes controlling semiconductor MBE growth. Scanning tunneling microscopy of submonolayer growth of Si on Si (100) has shown that surface diffusion is highly anisotropic [6,7]. The existence of a limiting thickness beyond which the film is not epitaxial, with a growth-rate-dependent activation energy, was observed by transmission electron microscopy (TEM) of Si MBE on Si(100) [8]. From the theoretical point of view, simu-lations based on the solid-on-solid model [9] showed that the thermally activated nature of surface diffusion determines the limiting thickness and its strong temperature dependence. W was postulated to build gradually with film thickness up to a saturation value, implying a continuous transition from smooth to rough surfaces. A different model, proposed by Kessle...

We discuss the use of admittance spectroscopy to measure the band offsets of semiconductor heterojunctions. By using this method to analyze the dynamic response of p-n junctions containing lattice-matched InP/Ga0.47In0.53As superlattices we can independently determine both the conduction- and valence-band offsets for this materials system. We find that the sum of these offsets equals the known band-gap difference between InP and Ga0.47In0.53As and that the ratio of the conduction-band offset to the valence-band offset is 42:58.