Growth Temperature Dependence of Indium Nitride Crystalline Quality Grown by RF-MBE

Abstract

PACS: 81.05.Ea; 81.15.HiWe have investigated the growth temperature dependence of InN crystalline quality grown by RF-MBE. It was confirmed that the crystalline quality improved by increasing the growth temperature within the dissociation limit of InN. We obtained FWHM as narrow as 3.7 cm --1 for E 2 (high frequency) phonon mode peak of Raman spectroscopy and 24 meV for the band-edge luminescence at 77 K. These values prove excellent quality of our samples. In this study, we obtained optical band-gap energy of around 0.8 eV at room temperature from the high-quality InN samples.Introduction The nitride semiconductors, GaN, AlN and InN, show many interesting physical properties. Among them, InN is considered to have the smallest effective mass, 0.14m 0 [1], and the highest electron drift velocity, 4.2 Â 10 7 cm/s [2]. Therefore, InN is very promising materials for channel layers in high-speed and high-frequency electronic devices such as hetero-structure field-effect-transistors (HFET). Compared with other compounds, however, InN has many unknown properties. For example, reported bandgap energy has a large discrepancy between $0.8 eV [3-7] and $1.9 eV [8][9][10]. From this viewpoint, it is now very important to grow high-quality single crystals to establish the fundamental properties of InN.We have previously reported that InN films with high-electron mobility were successfully grown by radio frequency plasma-excited molecular beam epitaxy (RF-MBE) using a low temperature InN buffer layer [11]. The growth temperature was optimized by in-situ observation of reflection high-energy electron diffraction (RHEED). In this paper, InN films have been grown at different temperatures without InN buffer layer. We tried to optimize the growth temperature by characterizing the crystalline quality by RHEED, Raman scattering, X-ray diffraction (XRD), Hall-effect, optical absorption, and photoluminescence (PL) studies.

Enhanced efficiency of Schottky-barrier solar cell with periodically nonhomogeneous indium gallium nitride layer

“…26,27 Recent theoretical studies, 28,29 along with an earlier experimental study, 30 have suggested that Schottky-barrier solar cells may be a particularly promising proposition if the semiconductor layer (i.e., the absorbing layer) was made from alloys of indium gallium nitride (In ξ Ga 1−ξ N), since the bandgap for these alloys can closely match the range of energies of photons across the entire solar spectrum (i.e., 0.70 to 3.42 eV) by varying the relative proportions of indium and gallium through the parameter ξ ∈ ð0;1Þ. 31 Specifically, indium nitride (i.e., ξ ¼ 1) has a bandgap of 0.7 eV 32,33 and absorbs efficiently across the infrared regime in the solar spectrum, while gallium nitride (i.e., ξ ¼ 0) has a bandgap of 3.42 eV and absorbs efficiently across the near-ultraviolet portion of the solar spectrum.…”

RF-Molecular Beam Epitaxy Growth and Properties of InN and Related Alloys

“…This supports the most recent proposal [21][22][23][24][25] that the fundamental band gap is about 0.8 eV, which is much lower than the commonly accepted value of 1.9 eV. The InN samples grown in this study were sent to UC Berkeley so that their optical properties could be characterized by optical absorption, PL, and photo-modulated reflectance techniques.…”

“…12 for InN films grown at 550, 530, 520, 500, and 460 C. The theoretically expected E 2 (high-frequency)-mode, E 2 (low-frequency)-mode and A 1 (LO)-mode are clearly observed at 491, 88, and 589 cm À1 , respectively. 25) The peak positions and FWHM of dominant E 2 (highfrequency)-phonon-mode peaks are summarized in Table II. The dependence of peak position on growth temperature may be due to the difference in residual stress between the films.…”

“…This FWHM is the narrowest value ever reported for InN films. 25) These results indicate that the crystalline quality was improved by increasing the growth temperature within the dissociation limit of InN.…”

“…These studies revealed that the fundamental band gap of single-crystalline InN was about 0.8 eV [21][22][23][24][25] instead of 1.9 eV, determined by optical absorption using polycrystalline InN.…”