Effects of Residual Carbon and Hydrogen Atoms on Electrical Property of GaAsN Films Grown by Chemical Beam Epitaxy

Abstract

The electrical behavior of nitrogen-hydrogen (N-H) complexes and carbon (C) atoms in GaAsN films grown by the chemical beam epitaxy (CBE) method have been studied by comparing H concentrations and hole concentrations. The contributions of H and C concentrations ([H] and [C]) to ionized impurity scattering have been also investigated. In the GaAsN films, there were three acceptor levels (A0, A1, and A2). The energy levels of A1 and A2 were 130 and 55 meV, respectively. The concentration of the deepest acceptor (A0) was more than 10 19 cm À3 , which was higher than [H] and [C]. A2 was observed only in films with a high [C]. The amount of A1 was proportional to [H]. Most of the residual H formed N-H complexes; thus, it is concluded that the N-H complex behaved as an acceptor in GaAsN films. At low temperatures, ionized impurity scattering limited the total hole mobility. The inverse numbers of the coefficients for the ionized scattering were consistent with [C] instead of [H]. This suggests that all the residual C atoms were ionized owing to compensation by the donors. A disagreement between N composition and alloy scattering has been also detected. This might indicate a fluctuation in the N composition in the GaAsN films.

Investigation of Lattice Defects in GaAsN Grown by Chemical Beam Epitaxy Using Deep Level Transient Spectroscopy

“…The thermal ionization energy of this energy level was estimated in the temperature range 70 to 100 K to be between 0.1 and 0.2 eV. It is in conformity with the theoretical calculations, which suggested the existence of a N-related hole trap acceptor-like defect with an activation energy within 0.03 and 0.18eV above the VBM of GaAsN (Janotti et al, 2003;Suzuki et al, 2008). Experimentally, a deep acceptor level, A2, was confirmed in CBE grown undoped GaAsN with ionization energies of E A1 = 130 ± 20 meV .…”

Effects of Mg doping on the electrical and luminescence characterizations of p-type GaAsN alloys grown by MBE

“…2(b). Similar bellshaped curves are observed for C-doped p-type GaAsN alloys grown by CBE [38], where C originates from metalorganic sources. Thus, the bell-shaped curves are probably common for p-type GaAsN alloys.…”

“…In addition, alloy scattering should be considered for alloy semiconductors. As for GaAsN alloys, several authors have reported that N atoms act as a scattering center probably due to a local fluctuation of N composition in GaAsN alloys from Hall-effect measurements [38,39]. It should be noted that the N composition of 1% corresponds to the N concentration of $2 Â 10 20 cm À 3 ; this N Activation energy E a is estimated to be 22(7 5) meV ( Fig.…”

“…3(b), the Hall mobility of GaAsN alloys is smaller than that of host GaAs, and the Hall mobility decreases with increasing N composition. This result suggests that N atoms act as a scattering center [38,39]. Therefore, this decrease in the Hall mobility is caused by the increase in the Mg impurity concentration and the alloy scattering due to N incorporation.…”

Relationship between a nitrogen‐related hole trap and ionized acceptors density in p‐type GaAsN grown by chemical beam epitaxy

“…Concerning E HC2 , it comes closer to the VBM of GaAsN with increasing [N] in the films. This can be explained through the Poole−Frenkel emission phenomenon, since the maximum magnitude of the electric field near the junction increases simultaneously with the junction capacitance and affects considerably the thermal emission of majority carriers from HC2 [7]. Further, the mean value of E HC2 is in conformity with the theoretical calculation and approximately identical to that calculated from the temperature dependence of free hole concentration in CBE grown p-type GaAsN [2,6].…”