Deep hole traps in Be-doped Al0.5Ga0.5As layers grown by molecular beam epitaxy

Abstract

Deep hole traps in p-type Al0.5Ga0.5As grown by molecular beam epitaxy have been studied by the deep-level transient-spectroscopy method applied to samples with a Schottky diode configuration. Five hole traps, labeled as H0 to H4, were found. For traps H1, H3, and H4 the activation energies for emission were ET1=0.14 eV, ET3=0.40 eV, and ET4=0.46 eV, respectively. Hole emission from trap H2 was dependent on the external electric field. The emission rate obeyed the Poole–Frenkel relation. When extrapolated to zero electric field, the thermal activation energy for hole emission was ET2,0=0.37 eV. Capture cross sections for traps H1 and H4 were thermally activated with energy barriers EB1=0.04 eV and EB4=0.18 eV, respectively.

Electrical characterisation of deep level defects in Be-doped AlGaAs grown on (100) and (311)A GaAs substrates by MBE

“…For analysis purposes, the trap energies are compared with published data. It is found that the traps H A2 and H E2 (0.145 ± 0.006 and 0.130 ± 0.01 eV), respectively, have almost the same activation energy as that of H 1 (0.14 eV) [ 11 ], but seem to be different in nature than that of H 1 . For example the capture cross-section of H 1 [ 11 ] was found to be temperature-dependent, whereas in this study the capture cross-sections of H A2 and H E2 are temperature insensitive.…”

“…It is found that the traps H A2 and H E2 (0.145 ± 0.006 and 0.130 ± 0.01 eV), respectively, have almost the same activation energy as that of H 1 (0.14 eV) [ 11 ], but seem to be different in nature than that of H 1 . For example the capture cross-section of H 1 [ 11 ] was found to be temperature-dependent, whereas in this study the capture cross-sections of H A2 and H E2 are temperature insensitive. However, H A2 shows electric field-dependent emission rate and obeys the Poole-Frenkel model (Figure 3 ) with constant α PF = 10.5 × 10 -5 eV(cm/V) 1/2 whereas, the carrier emission rate of H E2 are electric field-independent.…”

“…Similarly, traps H A3 , and H B4 (0.406 ± 0.006 and 0.400 ± 0.003 eV) have similar activation energy as that of H 3 (0.4 eV) [ 11 ]. A broad DLTS peak appeared within the temperature range 130-190 K and is resolved into three different peaks H C1 (0.356 ± 0.013 eV), H C2 (0.383 ± 0.003 eV) and H C3 (0.403 ± 0.003 eV) using Laplace DLTS technique.…”

Temperature dependence of Al0.2Ga0.8As X-ray photodiodes for X-ray spectroscopy

“…MBE growth of Be doped Al 0.2 Ga 0.8 As p layers is known to cause 0.4 eV and 0.46 eV traps within the temperature ranges of 200-225 K and 250-300 K, respectively. 27,28 Since the temperature range (253.15-313.15 K), at which the slope of À0.43 eV was measured, resides within the trap temperature region, it is likely that this is responsible. At sufficiently high temperatures, diffusion current will always dominate, 25 therefore Fig.…”

Low-frequency noise properties of p-type GaAs/AlGaAs heterojunction detectors

“…These fluctuations in carrier numbers due to trapping, and in some cases phonon scattering, lead to generation-recombination (G-R) noise. Studies of hole traps in unintentionally p-type doped GaAs layers have been investigated previously, 7 together with the lowfrequency noise properties of beryllium-doped GaAs/AlAs 1 quantum well and epitaxial layers of Al0.5Ga0.5As 8 …”