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Synthesis of thin surface layers of GaInAs on semi-insulating gaas by ion implantation.

Jafari, D. (1989) Synthesis of thin surface layers of GaInAs on semi-insulating gaas by ion implantation. Doctoral thesis, University of Surrey (United Kingdom)..

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In an effort to synthesize Ga(1-x)InxAs surface layers, Indium was implanted into semi insulating GaAs wafers at room temperature. Some samples were implanted with equal doses of indium and arsenic to preserve stoichiometry. Rutherford Backscattering Spectrometry (RBS) was mainly used for characterization. Other techniques such as Scanning Electron Microscopy (SEM), Photoluminescence (PL) and Secondary Ion Mass Spectrometry (SIMS) were also used. Indium was found to reach its solid solubility limit and to form metallic islands during ion implantation for high doses (4x1016 cm-2 and 2x1016 cm-2, with ion energies of 280 keV and 100 keV respectively). The maximum observed concentration of indium retained in GaAs was found to be about 3x1021cm-3. Some indium outdiffused and was lost due to ion sputtering. Neither rapid thermal annealing using a double graphite strip heater nor furnace annealing or a combination of both could incorporate substitutionally all of the retained indium in GaAs. During rapid thermal annealing some indium outdiffuses but is prevented from evaporating by the encapsulant. As a consequence, a large amount of indium is accommodated near the surface. On the other hand furnace annealing causes indiffusion and indium is distributed throughout the bulk. Metallic islands of indium were dissolved in hydrofluoric (HF) acid while removing the encapsulant. Most retained indium became substitutional when arsenic and indium were implanted in the same sample. The maximum indium that became substitutional was found to be about l.2x10 21cm-3 following an anneal at 650°C for one hour plus 920°C for 30 seconds. Electrical measurements showed that when selenium was implanted into such previously dual implanted GaAs, a higher electron concentration could be achieved compared to single implants of selenium in GaAs. A maximum electron concentration of about 6x1018cm-3 was obtained for the sample annealed at 650°C for one hour plus 960°C for 30 seconds. Both Hall effect and RBS showed that the Si3N4 encapsulant could withstand annealing cycles up to at least 950°C for 30 seconds or 800°C for 2 hours.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
Jafari, D.
Date : 1989
Contributors :
Depositing User : EPrints Services
Date Deposited : 09 Nov 2017 12:17
Last Modified : 20 Jun 2018 11:38

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