Transmutation doping and lattice defects in degenerate InSb

Abstract

n-type InSb single crystals were irradiated with thermal neutrons below T = 6 K. The Shubnikov-de Haas effect and the resistivity Q(T = 4.6 K) were measured as a function of the neutron dose and the holding temperature of a subsequent annealing program. The results are discussed in terms of the transport scattering rate and the lifetime of the Landau-levels. They have to be interpreted by means of n-doping due to nuclear reactions and irradiation induced negatively charged defects. Almost complete annealing of the transport parameters can be achieved by heating the samples to TA = 400 K. n-Typ InSb Einkristalle wurden unterhalb T = 6 K mit thermischen Neutronen bestrahlt. Der Shubnikov-de Haas-Effekt und der Widerstand Q(T = 4,6 K) wurden als Funktion der Neutronendosis bzw. der Haltetemperatur eines anschlieknden Erholungsprogramms gemessen. Die Ergebnisse werden anhand der Transportstreurate und der Lebensdauer der Landauniveaus diskutiert. Sie konnen durch n-Dotierung infolge von Kernreaktionen in Verbindung mit bestrahlungsinduzierten negativ geladenen Defekten interpretiert werden. Eine annihernd vollsthdige Ausheilung der Transportparameter kann durch Tempern der Proben bei TA = 400 K erreicht werden.

Shubnikov-de Haas effect study of InAs after transmutation doping at low temperatures

“…Low-temperature neutron irradiation of InSb-a material very similar to InAsleads, in sharp contrast with the results reported above, to a decrease in the conduction electron density in spite of the transmutation doping by donors and a large increase in the resistivity as a function of the thermal neutron dose [ 5 ] . From the analysis of these data it was deduced that in InSb the In vacancy (again being the most common irradiation defect) should act as a trapping centre for two electrons.…”

“…The Dingle temperatures X of the InAs samples have been determined by fitting the sdH oscillation profiles at fixed measuring temperature [5]. For unirradiated specimens the X-values were found to increase with increasing carrier density exhibiting values between 10.4 k 0.5 K (no = 6.8 X 10l6 ~m -~) and 14.3 t 0.9 K (no = 1.3 X lo1' ~m -~) .…”

“…In the experiments described above, the neutron transmutation doping leads to an irreversible change in the conduction electron density and the electrical resistivity. The irradiation damage and the annealing behaviour of InAs will therefore be discussed in terms of the scattering rates ti' = p n e 2 / m * ( 5 ) and temperature TA, The increased 5; ' due to ionised impurity scattering by the transmutationenhanced dopant concentration is given as full square. This value has been evaluated using equation (7).…”

“…In all cases the measuring temperature was 4.2 K. A detailed description of the experimental set-up and the data analysis has been published previously [5].…”