Radiation induced carrier enhancement and intrinsic defect transformation in n-GaAs

Abstract

Gallium arsenide grown by the metallorganic chemical vapor deposition method and n doped with silicon to a concentration of 1015 cm−3 was exposed to reactor neutron irradiation in the 1012 to 3×1014 cm−2 1 MeV equivalent fluence range. Studies of the defects through deep level transient spectroscopy (DLTS), photoluminescence (PL), and transport measurements on this material indicate correlation between the nature and density of defects, and some of the transport parameters. Contrary to the general perception of degradation of electronic properties of semiconductors on nuclear irradiation, we observe enhancement in some of the electrical/optical properties of GaAs on irradiation at lower fluence levels. These properties degrade on irradiation at higher fluences. The PL intensity of irradiated GaAs increases over the 1×1012 to 1×1013 cm−2 fluence range. At 1×1013 cm−2, the increase in the signal from different PL peaks ranges from 25% to 200%. Similarly, the carrier density of irradiated GaAs, as determined by transport measurements, increases by about 25% on irradiation at 3×1012 cm−2, before decreasing at and above 3×1013 cm−2 fluence. The density of the EL2 trap as determined through the DLTS technique, remains constant with fluence and that of the EL12 trap at 780 meV below the conduction band decreases at an injection ratio of −0.5±0.3 cm−1 up to ≂1×1014 cm−2 fluence. The EL6 trap at 0.38 meV below the conduction band is introduced at a rate of 0.30±0.04 cm−1. Thus, neutron irradiation restructures the deep levels, with the consequence that the carrier density goes through a maximum at low fluence levels. Through PL measurements, the maximum in carrier density corresponds to a fluence level of (1.0±0.2)×1013 cm−2. At fluences above 1014 cm−2, we observe the introduction of a deep level at 260±85 meV below the conduction band (EL14) at a rate of 1.7±0.4 cm−1. Above 1014 cm−2, we observe an increase in carrier depletion in GaAs through PL and transport measurements.

Influence of electron irradiation on p-n junctions in SiGe superlattices

“…A slight improvement of the ideality factor and saturation current at small fluences may be interpreted as the known “low‐dose effect” , occurring due to a dissolution of native structural defects (caused by the non‐equilibrium character of the MBE growth technology), assisted by irradiation‐induced mobile point defects.…”

Structural and optical changes in GaAs irradiated with 100 keV and 2 MeV protons

“…In the past few decades, photoluminescence (PL) spectroscopy has been employed to study the influence of particle irradiation on the luminescence properties of GaAs, including neutrons and high-energy protons [19][20][21][22][23][24][25], but few studies have been conducted using low-energy protons. Hanna et al [19,20] irradiated n-type GaAs materials with 60 Co, γ photons, electrons, protons, He ions, Li ions, D ions, and O ions, and then analyzed the defects caused by particle irradiation using low-temperature PL spectrum.…”

“…In addition, the study also shows that larger the mass and lower the energy of the incident particle, the more defects can be generated. Jorio et al [21,22] studied the degradation of luminescence properties of n-type GaAs irradiated by neutrons using low-temperature PL spectroscopy. It was found that neutron irradiation introduced shallow donors and deeplevel defects in n-type GaAs.…”

DC electrical performance improvement of AlGaAs/InGaAs PHEMTs by using low thermal neutron radiation dose

“…A degradation of electrical performance of devices has usually been observed for a total dose greater than 1 × 10 15 neutrons/cm 2 [5]. On the other hand, an improvement of the electronic properties of GaAs material has been observed after an irradiation with low neutron fluences (3 × 10 12 neutrons/cm 2 ) [6]. The improvement of some bulk properties of GaAs material at low fluence irradiation has also been correlated with a high defect removal rate [7].…”