Showing papers by "Stephen J. Pearton published in 1984"

Bulk acceptor compensation produced in p‐type silicon at near‐ambient temperatures by a H2O plasma

Abstract: We report the neutralization of the shallow acceptors boron and gallium in p‐type silicon to a depth >1 μm after exposure to a H2O plasma for 3 h at temperatures as low as 80 °C. The fact that uncompensated n‐type silicon is unaffected by the plasma treatment means that donor formation is excluded. Exposure to either O2 or H2 plasmas does not lead to acceptor removal; however, sequential treatment in an O2 plasma followed by a H2 plasma produces the same effect as the H2O plasma while the inverse sequence has no effect. Our observations can be explained with a model considering rapidly diffusing atomic oxygen and hydrogen which recombine on acceptor sites forming neutral A−OH+ complexes. The model shows that acceptor compensation kinetics is dominated by the diffusion of atomic hydrogen.

Hydrogenation of gold‐related levels in silicon by electrolytic doping

Abstract: The deep gold‐related donor and acceptor levels in silicon have been neutralized to several μm depth by introducing atomic hydrogen using an electrolytic method. Using phosphoric or sulfuric acid as the electrolyte, it is possible to dope the crystalline silicon with hydrogen at elevated temperatures (200–280 °C) allowing direct comparison with other means of introduction, such as hydrogen plasma exposure. We find the electrolytic method is not as efficient as plasma treatment for the same conditions, possibly due to oxide formation during the immersion in the acid.

Deuterium in germanium: Interaction with point defects

Abstract: Electrical measurements on deuterium plasma‐treated germanium samples containing deep level recombination centers show significant neutralization of these defects to depths of ∼80 μm. Chemical measurement of the deuterium profile after similar plasma treatment shows apparent incorporation depths of ∼0.2 μm. We discuss experiments which resolve this discrepancy, and show that hydrogen diffusion into the bulk of the germanium is responsible for the observed neutralization.

Low-temperature oxygen diffusion in silicon

Abstract: Using the formation of the proposed neutral acceptor‐hydroxyl complex AOH as a marker, the diffusion coefficient of a mobile oxygen species introduced in p‐type silicon from a plasma source at near ambient temperatures is determined to be D0=3.0×10−10 exp(−3.0/kT) cm2 s−1. At 35 °C the diffusion of this unbound oxygen species is 30 times faster than the effective diffusion of atomic H introduced in a similar manner. An activation energy of 1.60 eV is found for the thermal dissociation of this oxygen species bound to boron.

Rapid Annealing of GaAs and Related Compounds

Abstract: In recent years, rapid annealing of GaAs has been employed to activate ion implanted dopants and to produce metal-semiconductor contacts. More recently, rapid heating techniques have been used to anneal heterostructures without degrading requisite high mobilities of SDHT devices. This paper reviews the various annealing regimes which are useful for heat treating GaAs and related compounds. Examples are chosen which illustrate unique and potentially useful features of rapid annealing.

Annealing characteristics of neutron‐transmutation‐doped germanium

Abstract: The effects of thermal‐ and injection‐enhanced annealing on the electrical properties of initially high‐purity (NA−ND =1010 cm−3) neutron‐transmutation‐doped (NTD) Ge were investigated using capacitance transient spectroscopy and variable temperature Hall effect. Complete recovery of electrical properties was observed after thermal annealing at 400 °C for 6 h, and significant activation of dopants created by the NTD process is seen even in samples left at ambient temperature for eight months after irradiation. Electric field‐enhanced emission of trapped holes from deep level, damage‐induced states was used to verify their acceptor nature, and a recombination‐enhanced annealing mechanism was observed for several deep acceptors. Other high‐purity samples irradiated with a lower dose of fast neutrons only (average energy 4.2 MeV) showed many deep hole traps, most of which were tentatively correlated with the amount of hydrogen in the parent crystal. These deep level damage centers were not observed in the mo...

The nature of the dominant γ-induced defects in high-purity germanium

Abstract: For relatively low Co-60 γ-irradiation doses (3 × 1015 γ cm−2) and dose rates (20 × 1010 γ cm−2 sec−1), two hole traps (E v+023 eV, E v+038 eV) are the dominant defects introduced in highpurity p-type germanium A comprehensive study involving crystals grown under a wide variety of conditions supports the hypothesis that these centers are most likely due to complexes between oxygen and lattice vacancies Injection-enhanced annealing was observed for both these holetrapping states, and a discussion is given of the seemingly dose-dependent nature of the defects produced in γ-irradiated high-purity p-type germanium

Quenched-in deep acceptors in germanium

Abstract: Quenching from temperatures in the range 500-750 degrees C of high-purity p-type germanium induces a deep hole trapping state at Ev+0.23 eV. This level is also seen in gamma -irradiated samples from the same material, and is tentatively identified as an oxygen-vacancy complex. Quenching from 700 degrees C of copper-doped germanium induces the normal Cu-, Cu2- and Cu-H levels, as well as a deep hole trap at Ev+0.41 eV. Field-assisted emission measurements are consistent with this level being due to triply ionised copper.

Deep Level Impurities in Germanium and Silicon: Low Temperature Passivation or Removal Techniques

Abstract: Deep level impurities and defects in high-purity germanium and silicon radiation detectors are often the cause of degraded spectral resolution. Exposure of the semiconductor diode to a low pressure hydrogen plasma may neutralize the electrical activity of a wide range of line and point defects and contaminating impurities, such as copper in Ge and gold in Si. The efficiency and thermal stability of this technique are discussed. The application of other novel methods of defect removal, such as the room temperature drifting of charged defects out of the depletion region under the action of the electric field in a diode, and the recombination enhanced annealing of radiation damage centers in Ge is also discussed.