Melt-grown p-type GaAs with iron doping

Abstract

Optical and electrical properties are described for bulk GaAs, grown from a melt doped with iron to create FeGa deep acceptors in a sufficient amount (exceeding the EL2 defect concentration) to make high-resistivity p-type rather than semi-insulating material. Both iron photoionization and EL2+ photoneutralization contribute to the near-infrared optical absorption. This made it possible to deduce the concentrations (NAi and NAn) of ionized and lattice-neutral iron, and the ratio (NAi/NAn). Temperature dependent measurements of dc electrical transport yielded quantities such as the free hole density, and hence the Fermi energy, for the 290–420 K range. This information combined with (NAi/NAn) led to a determination of the iron acceptor’s free energy εA(T): about 0.46 eV above the valence band at 300 K, and ∼40 meV closer at 420 K. The temperature dependence of εA for iron is shown to differ from εv, εc, midgap, or the free energy for CrGa acceptors in GaAs.

Time-resolved micro-photoluminescence studies of deep level distribution in selectively regrown GaInP:Fe and GaAs:Fe

“…In GaAs grown by molecular beam epitaxy at low temperature (200-300 • C), the concentration can be as high as 10 19 cm −3 [26]; however, in GaAs layers grown under normal conditions it is of the order of 10 16 cm −3 [21,27]. This means that for the nominal Fe concentration of 5 × 10 17 cm −3 used in the Fe-doped GaAs layer, all the EL2 centres will be ionized, and the number of ionized Fe centres (Fe 2+ ) will be equal to the number of EL2 defects [28]. For undoped regrown GaAs layers, the concentration of ionized EL2 will be determined by unintentionally incorporated acceptors.…”

Charge storage characteristics of pnp GaAs layers prepared by iron diffusion

“…Iron atoms, when doped in the crystal of gallium arsenide, form a deep acceptor level at 0.46 eV above the top of the valence band [1]. This means that iron doping into lightly doped n-type GaAs could render the crystal a weak p-type (p-type) by overcompensation of donors [2,3].…”

Higher Picosecond Photoresponsivity Realized by Introducing Hole-Capturing Levels of Iron in GaAs

“…2) Because of their donorlike nature, they have a much larger capture cross section for electrons than for holes, i.e., σ n σ p . 5) On the other hand, iron forms a deep acceptor level in GaAs at E v + 0.46 eV, 6) and the level tends to capture holes rather than electrons, i.e., σ n σ p . 7,8) Hence, it is expected that iron doping of the SI wafer can control the transient lifetimes as well as its resistivity through transient carrier capturing and carrier compensation at equilibrium, respectively.…”