Medium-deep acceptors in LEC GaAs

By TSC and TDH measurements on medium-resistivity p-type GaAs grown by the LEC and the SSD method, three hole traps (acceptors) with activation energies between 0.3 and 0.5 eV can be detected beside some deep electron traps. Both the hole and the electron traps occur in undoped n-type LEC GaAs, too. It is shown that these acceptors are not due to Fe or Cu. Annealing experiments with n-type samples yield that by this procedure the concentration of hole traps is enhanced whereas the electron-trap concentration decreases. This leads to an increase of the TDH-activation energy due to changes compensation. For the acceptor at Ev + 0.44 eV the temperature coefficient of the activation energy (EA = EAO – αT) could be determined to α = (2.2 ± 0.3) × 10−4 eV/K. Mittels TSC- und TDH-Messungen an mittelohmigem p-leitendem GaAs, das mit Hilfe der LEC- bzw. der SSD-Methode gezuchtet wurde, konnen neben einigen Elektronentraps drei Lochertraps (Akzeptoren) mit Aktivierungsenergien zwischen 0,3 und 0,5 eV nachgewiesen werden. Sowohl die Locher- als auch die Elektronentraps treten ebenfalls in undotiertem n-leitendem LEC-GaAs auf. Es wird gezeigt, das diese Akzeptoren nicht auf Fe oder Cu zuruckzufuhren sind. Temperexperimente mit n-leitenden Proben liefern, das durch diese die Konzentration der Lochertraps erhoht wird, wahrend die Elektronentrap-Konzentration abnimmt. Dies fuhrt zu einer Erhohung der TDH-Aktivierungsenergie infolge geanderter Kompensation. Fur das Akzeptorniveau bei Ev + 0,44 eV wird der Temperaturkoeffizient der Aktivierungsenergie (EA = EAO – αT) zu α = (2,2 ± 0,3) × 10−4 eV/K bestimmt.

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