Effect of N Incorporation on Growth Behavior of InGaAsN/GaAs/Ge Multi-Layered Structure by MOVPE

Abstract

We have investigated an effect of N incorporation on InGaAsN on Ge (001), which is proposed to be a part of the InGaP(N)/InGaAs/InGaAsN/Ge four-junction solar cell, and on its growth behavior. Results obtained from high resolution X-ray diffraction and Raman scattering demonstrated that high quality In0.11Ga0.89As1-yNy films with N (y) contents up to 5% were successfully grown on n-type doped Ge (001) substrate by metalorganic vapor phase epitaxy using low-temperature (500°C) GaAs buffer layer. As expectation, the In0.11Ga0.89As0.96N0.04 film is examined to be under lattice-matching condition. Anti-phase domains were observed for the film without N incorporation, which exhibits submicron-size domains oriented along the [110] direction on the grown surface. With increasing N content, the domains become less orientation, and present in a larger domain size. Based on results of transmission electron microscopy, a high density of anti-phase domains was clearly observed at the interface of low-temperature GaAs buffer layer and Ge substrate. On the other hand, it is found to drastically reduce within the N-contained InGaAsN region. Furthermore, the lattice-matched In0.11Ga0.89As0.96N0.04 film is well developed to reduce the density of anti-phase domains.

TEM Analysis of Planar Defects in InGaAsN and GaAs Grown on Ge (001) by MOVPE

“…2(b) with the g-vector of (a) = ( 002 surface. Therefore, it is possible to form APBs, which consist of Ga-Ga or As-As bonds along the [001] direction as shown in the model reported in the previous work [8]. Moreover, we cannot prove the APDs structure in all micrographs because ultrathin of the TEM specimen thickness and low specimen tilt angle are needed.…”

“…However, I. Németh et al [4] reported the optimization of dark field TEM imaging condition for the detection of APDs structure in GaP film grown on Si substrate. In the previous work, we have investigated In 0.11 Ga 0.89 As 1-y N y films with N (y) contents up to 5% grown on n-type doped Ge (001) substrate [5]. When the N content in the InGaAsN grown films is increased the surface domains, which are related to APBs, become less orientation showing a larger size.…”

“…When the N content in the InGaAsN grown films is increased the surface domains, which are related to APBs, become less orientation showing a larger size. The lattice-matched InGaAsN film was developed to reduce a density of APDs, which were mainly observed at GaAs/Ge interface [5]. In the present work to analyze the planar defects in the lattice-matched InGaAsN film grown on GaAs/Ge (001) substrate, TEM method particular the dark field mode was performed.…”

Influences of two-step growth and off-angle Ge substrate on crystalline quality of GaAs buffer layers grown by MOVPE

“…Presently, an InGaP/InGaAs/InGaAsN/Ge four-junction solar cell with a lattice-matched InGaAsN absorber layer is expected to have a conversion efficiency of over 40% [5,6]. The difficulty of the epitaxial growth of InGaAsN on Ge, which respectively are polar and non-polar semiconductors, is to prevent the formation of APDs [7,8]. Therefore, a GaAs buffer layer is required to obtain a high quality InGaAsN layer on a Ge substrate as well as to create an n-type or a p-type junction to the Ge substrate [9].…”