Metal-organic chemical vapor deposition of single domain GaAs on Ge/GexSi1−x/Si and Ge substrates

Abstract

The current work investigates the sublattice orientation of GaAs on (001) Ge/GexSi1−x/Si and Ge substrates offcut 6° to [110] as a function of atmospheric pressure metal-organic chemical vapor deposition (MOCVD) nucleation conditions. Anisotropic sidewall etching of the GaAs films and differential interference contrast microscopy of the GaAs film surface reveal a 90° sublattice rotation between the two possible GaAs phases. One sublattice orientation dominates at film nucleation temperatures >600 °C, another dominates at nucleation temperatures <500 °C. Incomplete transition between the two sublattice orientations during pregrowth thermal cycling accounts for the appearance of localized bands and clouded regions of antiphase disorder, marking a shift in the polarity of the GaAs film. We have concluded that the observed domain rotation results from a temperature-dependent surface transition prior to actual GaAs nucleation. In particular it is suspected that background arsenic levels in the MOCVD system induce the observed transition. We propose that localized antiphase disorder reflects kinetically limited arsenic dimer orientation on the prenucleation germanium surface. Conditions for the complete suppression of antiphase disorder under optimized growth conditions are described and demonstrated by transmission electron microscopy.

Epitaxial growth of antiphase boundary free GaAs layer on 300 mm Si(001) substrate by metalorganic chemical vapour deposition with high mobility

“…33 Nevertheless, this value is still high and must be reduced in the future. Several methods are possible to decrease the threading dislocation density down to 10 5 -10 6 cm −2 : Thermal Cycling Annealing (TCA) of the layer, 2,8 Ge/SiGe buffer layer, 13 ART, 10-12 superlattices, 2 InAs quantum dots insertion in the layer. 9 Then, the influence of APBs on the optical and electrical properties has been studied.…”

“…This is definitively correlated with the role of APBs that act as non-radiative recombination centers. 13 In order to study the role of APBs on the electrical properties, a 250 nm thick Si-doped GaAs layer with a doping level of n = 7 × 10 17 cm −3 was grown on a GaAs substrate and on 400 nm thick GaAs buffer layers (n = 3 × 10 16 cm −3 ) with and without APBs. Hall effect measurements in the Van der Pauw configuration are reported in Table II. For the APB-free Si-doped GaAs layer, the mean electron mobility (µ e ) was evaluated by taking 5 points across whole 300 mm wafer to be 2000 ± 60 cm 2 /V s, while the one measured for the sample containing APBs was only 200 cm 2 /V s, which represent an improvement of one decade.…”

“…To reduce crystalline defects density, various smart improvements have been investigated like post-growth thermal cycle annealing, 2,8 insertion of dislocation filter layer, 9 selective growth in trenches using aspect ratio trapping (ART) method [10][11][12] or Ge/GeSi buffer layer. 13 The second challenge is the difference of thermal expansion coefficients between Si and III-V (6.6 × 10 −6 K −1 and 2.3 × 10 −6 K −1 for GaAs and Si, respectively), which limits the film thickness before crack appears. The third one is the emergence of anti-phase domains at the interface between III-V and Si substrate.…”

Direct and indirect band gaps in Ge under biaxial tensile strain investigated by photoluminescence and photoreflectance studies

“…• towards the [110] direction in order to minimize the formation of antiphase domain boundaries [36,37], were first desorbed of native oxide at 750…”

GaAsP/InGaP heterojunction bipolar transistors grown by MOCVD

“…This particular offcut was chosen because GaAsP or GaAs grown at temperatures above 600 °C on (100) SiGe or Ge, respectively, with a 6° offcut towards the nearest <111> direction will adopt this orientation. 9 A tensile GaAsxP1-x compositionally graded buffer was used to reach the desired lattice constant for the final device layers. A compositional grade rate of 0.2% strain/µm was used, resulting in buffer thicknesses varying from 0 nm ( = 1) to 4 µm ( = 0.825).…”