K.‐H. Goetz

Bio: K.‐H. Goetz is an academic researcher from RWTH Aachen University. The author has contributed to research in topics: Epitaxy & Substrate (electronics). The author has an hindex of 3, co-authored 4 publications receiving 327 citations.

Optical and crystallographic properties and impurity incorporation of GaxIn1−xAs (0.44<x<0.49) grown by liquid phase epitaxy, vapor phase epitaxy, and metal organic chemical vapor deposition

Abstract: Optical, crystallographic, and transport properties of nominally undoped n‐type and Zn doped p‐type Gax In1−xAs /InP (0.44

Deep Fe and intrinsic defect levels in Ga0.47In0.53As/InP

Abstract: Two deep traps in Ga0.47In0.53As/InP:Fe at a depth of 110 meV and 150 meV, respectively, are observed for the first time using low‐temperature photoluminescence and deep level transient spectroscopy. The dependence of luminescence intensity on the growth process itself (liquid phase epitaxy, vapor phase epitaxy, and metalorganic chemical vapor deposition) and its parameters (growth temperature, layer thickness) and the substrate doping is reported and leads to the unambigous identification of the 150‐meV acceptorlike trap as being caused by Fe impurities. Fe diffuses from the substrate to the epitaxial layer during the growth process. This outdiffusion is less pronounced for layers grown at lower temperature. The level at 110 meV which is also observed in layers grown on InP:S substrate is tentatively assigned to an intrinsic defect of Ga0.47In0.53As.

High resolution capacitance spectroscopy of LPE In0.53Ga0.47As grown on Fe doped InP-substrate and VPE GaAs grown on Cr-doped GaAs-substrate

Abstract: A DLTS-system with largely improved performance has been realized: dC min = 13·10 -18 F >, reponse time = 5 μ s, dC/C o = 3·10 -8 . The influence of different s.i. GaAs substrate materials on the quality of epitaxial layers is assesses. Depth profiles of deep levels in GaAs Schottky diodes caused by the gate metallization are measured with a depth resolution better than 10nm. A deep acceptorlike trap at E y +150meV is discovered in thin In 0.53 Ga 0.47 As layers grown on Fe-doped InP. The trap is most probably caused by outdiffusion of Fe from the substrate.

Band parameters for III–V compound semiconductors and their alloys

Abstract: We present a comprehensive, up-to-date compilation of band parameters for the technologically important III–V zinc blende and wurtzite compound semiconductors: GaAs, GaSb, GaP, GaN, AlAs, AlSb, AlP, AlN, InAs, InSb, InP, and InN, along with their ternary and quaternary alloys. Based on a review of the existing literature, complete and consistent parameter sets are given for all materials. Emphasizing the quantities required for band structure calculations, we tabulate the direct and indirect energy gaps, spin-orbit, and crystal-field splittings, alloy bowing parameters, effective masses for electrons, heavy, light, and split-off holes, Luttinger parameters, interband momentum matrix elements, and deformation potentials, including temperature and alloy-composition dependences where available. Heterostructure band offsets are also given, on an absolute scale that allows any material to be aligned relative to any other.

Effects of Ga addition to CuInSe2 on its electronic, structural, and defect properties

Abstract: Using a first-principles band structure method we have theoretically studied the effects of Ga additions on the electronic and structural properties of CuInSe2. We find that (i) with increasing xGa, the valence band maximum of CuIn1−xGaxSe2 (CIGS) decreases slightly, while the conduction band minimum (and the band gap) of CIGS increases significantly, (ii) the acceptor formation energies are similar in both CuInSe2 (CIS) and CuGaSe2 (CGS), but the donor formation energy is larger in CGS than in CIS, (iii) the acceptor transition levels are shallower in CGS than in CIS, but the GaCu donor level in CGS is much deeper than the InCu donor level in CIS, and (iv) the stability domain of the chalcopyrite phase increases with respect to ordered defect compounds. Our results are compared with available experimental observations.

Effect of mismatch strain on band gap in III‐V semiconductors

Abstract: Interfacial elastic strain induced by the lattice parameter mismatch between epilayer and substrate results in significant energy–band‐gap shifts for III‐V alloys. The epilayers used in this study are GaxIn1−xAs on (100) InP and GaxIn1−xP on (100) GaAs prepared by organometallic vapor phase epitaxy. For layer thicknesses between 1 and 1.5 μm, and Δas.f./a0≤3.5×10−3 the misfit strain is assumed to be accommodated elastically. The energy–band‐gap shifts are determined by comparing the photoluminescence peak energies of the epilayers with the best experimental relation of band gap versus composition for unstrained layers. A calculation of the energy–band‐gap shift due to biaxial stress made for GaxIn1−xAs is found to agree with the photoluminescence measurements. In addition, a comparison of the energy–band‐gap shift for GaxIn1−xP shows a clearly different dependency for tensile and compressive strain, in good agreement with calculated results.

Optical transitions and carrier relaxation in self assembled InAs/GaAs quantum dots

Abstract: We present experimental results concerning optical transitions and carrier dynamics (capture and relaxation) in self assembled InAs/GaAs quantum dot structures grown by metalorganic vapor phase epitaxy.Photoluminescence(PL) measurements at high excitation level reveal optical transitions above the ground state emission. These transitions are found to originate from occupied hole states by solving the quantum doteigenvalue problem. Time‐resolved studies after non‐resonant pulse excitation exhibit a relaxation ladder of the excited carriers from the GaAs barrier down to the ground state of the quantum dots. From both the continuous‐wave measurements and the PL‐decay curves we conclude that the carrier relaxation at non‐resonant excitation is mediated by Coulomb interaction (Auger effect). PL‐decay curves after resonant pulse excitation reveal a longer rise time compared to non‐resonant excitation which is a clear indication of a relaxation bottleneck inside the quantum dots. We interpret the rise time (≊ 400 ps) in this case to originate from relaxation via scattering by acoustic phonons. The PL‐decay time of the ground state emission ≊700 ps is interpreted as the excitonic lifetime of the quantum dot.