Electrical properties of high energy 120Sn implantation in GaAs

Abstract

Single crystal n-GaAs substrates have been implanted at room temperature with 120Sn ions at an energy of 70 MeV. The optical microscope and scanning electron microscope studies of the cross section of the implanted samples have shown the formation of two sharp layers at a depth of 8.7 and 11 μm from the surface of the substrate. The electrical characteristics of the Schottky diodes fabricated on the implanted substrates at room temperature indicate the presence of high series resistance due to radiation defects. The electrical properties of the implanted samples were investigated after implantation and annealing to 850 °C. Low temperature resistance measurements of these samples indicate that the samples annealed to 450 °C are dominated by a variable range hopping conduction mechanism, whereas for the samples annealed at 550 and 650 °C the electrical conduction is due to hopping between the neighboring defect sites. At annealing temperatures higher than 650 °C, the electrical transport below room temperature seems to be dominated by carriers in the extended states, which are also responsible for the electrical conduction at room temperature and above, for the samples annealed at temperatures higher than 450 °C.

Ion beam induced surface and interface engineering

“…It has been demonstrated that the minority carrier life time can be reduced significantly by introducing deep level defects in Si and it is possible to improve the switching characteristics of the diodes [17].…”

Investigations of the Electrical and Structural Characteristics of 50 MeV7Li Implanted SI-InP

“…For the annealing temperatures 623 and 723 K the sheet resistivity increases and the sheet carrier concentration decreases. This may be due to 7 Li occupying the indium 162 N. Dharmarasu et al 7 Li and/or interaction of 7 Li with defects in general displacing 7 Li from its interstitial position. There was only a small decrease in the mobility of the implanted samples and annealing causes little increase in the mobility.…”

“…In germanium and silicon, 7 Li acts as a shallow interstitial donor and it has large diffusion coefficients [1]. However, it shows a different behavior in GaAs either as a donor or as an acceptor according to the type of conduction.…”

“…Wahl et al [4] have established that the 7 Li atoms are located in the tetrahedral interstitial sites within four phosphorus atoms in SI-InP samples, implanted at room temperature. In the case of high temperature implanted samples, 7 Li atoms occupy a substitutional site (mostly indium site). High energy implantation into SI-InP is needed to produce active and/or compensating layers required for the fabrication of microwave devices [5,6].…”

“…High energy ion implantation has attracted considerable attention in the fabrication of special device structures that require deep conductive layers. Many of these devices are sensitive to electrically active defects and therefore investigations of the defect production by high energy ion implantation and annealing on their electrical characteristics are desirable [7]. Recently, the high energy heavy ion implantation-induced effect has been studied in GaAs [7] and in high energy 28 Si irradiated in silicon [8,9].…”