Electrical isolation of GaAs by light ion irradiation damage

Journal of Applied Physics

Coelho

Souza

2002

Self Cite

The electrical isolation of p-type GaAs layers doped with acceptor impurities incorporated in the Ga sublattice ͑Mg͒ or As sublattice ͑C͒ was studied using proton bombardment. It was found that practically the same proton dose is required to reach complete isolation ͑isolation threshold dose, D th ͒ in layers doped with either Mg or C of comparable original sheet hole concentration (p s ). This result is evidence that the sublattice where the acceptor dopant atoms are incorporated does not play any significant role for the isolation formation process in GaAs. The behavior of the recovery of the conductivity during subsequent thermal annealing was found very similar in Mg and C doped samples irradiated to equal proton doses. In samples irradiated to doses ϽD th , the sheet resistance (R s ) increases during annealing at temperatures Ͼ100°C, reaches a maximum at Х200°C, and then decreases progressively toward the original value. For proton doses ranging from D th to 5D th , the isolation is preserved up to the temperature of Ϸ500°C. The temperature of Ϸ700°C was found to be the upper limit for the thermal stability of the isolation in samples irradiated to doses of 100 D th .

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 95%

Electrical isolation of p-type GaAs layers by ion irradiation

Journal of Applied Physics

Coelho

Souza

2002

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“…8 Isolation of n-type and p-type GaAs layers of similar original sheet carrier concentration is attained after implantation of identical ion doses. 9 This result was explained assuming that conduction electrons and holes are trapped by acceptor and donor centers, these centers being related to Ga and As antisite complex defects, respectively. Because the displacement energies of Ga and As are almost equivalent, 10 similar concentrations of both antisite defects are formed in the collision cascades and hence similar concentrations of electron and hole traps are created.…”

Section: Introductionmentioning

confidence: 99%

Characterization of deep level traps responsible for isolation of proton implanted GaAs

Journal of Applied Physics

Coelho

Tan

et al. 2003

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Deep level transient spectroscopy was employed to determine the electrical properties of defects induced in metalorganic chemical-vapor deposition grown n-type and p-type GaAs during proton bombardment. Thermal stability of these defects was investigated and correlation with defects responsible for isolation of GaAs by ion bombardment was discussed. The annealing temperature region ͑220-250°C͒ is similar to proton isolated GaAs below the threshold dose for complete isolation. At least four of the five traps observed in n-type GaAs are not simple interstitial-vacancy pairs. For p-type GaAs we have observed an unknown level with apparent energy of ϳ0.64 eV.

“…The isolation is considered to be stable at a given temperature if R s persists at Ϸ10 9 ⍀/sq after annealing at that temperature. Figure 2 presents evolution of R s with the annealing temperature of the implanted n-type resistors using four different doses: 6ϫ10 13 cm Ϫ2 (D th ); 3ϫ10 14 cm Ϫ2 (5D th ); 1ϫ10 15 cm Ϫ2 (17D th ), and 1 ϫ10 16 cm Ϫ2 (167D th ).…”

mentioning

confidence: 99%

“…Similar results are obtained for p-type AlGaAs. Figure 3 compares the maximum temperature of stability for isolated n-and p-type AlGaAs ͑this work͒ with isolated n 10 and p-type 13 GaAs. The general trend of this graph shows that the thermal stability increases with an increase in dose ratio.…”

mentioning

confidence: 99%

Electrical isolation of AlxGa1−xAs by ion irradiation

Lippen

Applied Physics Letters

Tan

et al. 2002

Self Cite

The evolution of sheet resistance Rs of n-type and p-type conductive AlxGa1−xAs layers (x=0.3, 0.6, and 1.0) during proton irradiation was investigated. The threshold dose Dth to convert a conductive layer to a highly resistive one is slightly different for n- and p-type samples with similar initial free carrier concentration and does not depend on the Al content. The thermal stability of the isolation, i.e., the temperature range for which the Rs is maintained at ≈109 Ω/sq, was found to be dependent on the ratio of the carrier trap concentration to the original carrier concentration. The thermal stability of isolated p-type samples is limited to temperatures lower than 450 °C. The temperature of ≈600 °C is the upper limit for the n-type samples thermal stability.