No abstract

Articles you may be interested inElectron and hole deep levels related to Sb-mediated Ge quantum dots embedded in n-type Si, studied by deep level transient spectroscopy Appl. Phys. Lett. 102, 232106 (2013); 10.1063/1.4809595 Improved calculation of vacancy properties in Ge using the Heyd-Scuseria-Ernzerhof range-separated hybrid functional Schottky barriers formed by depositing Au on n-type Ge have been used to study the antimony-vacancy complex ͑E center͒. Both hole and electron transitions have been observed because the formation of an inversion layer at the semiconductor surface enables minority carriers to be injected when the Schottky barrier is forward biased. It is argued that the E center in Ge has three charge states: double negative, single negative, and neutral. The free energy of electron ionization for the double acceptor level of the complex has been found to be ⌬G(ϭ/Ϫ)ϭ0.294 Ϫ4.2 kT (eV), where k is Boltzmann's constant. Consequently, the position of the double acceptor level of the E center ͕E(ϭ/Ϫ)ϭE c Ϫ⌬G(ϭ/Ϫ)͖ is temperature dependent. In moderately Sb-doped (N Sb ϭ10 13 -10 15 cm Ϫ3 ) Ge crystals at equilibrium conditions half-occupancy of the double acceptor state of the Sb-V complex occurs when the Fermi level is at about E c Ϫ0.20 eV. The single acceptor level of the E center is in the lower part of the band gap. The activation energy of hole emission from the E(Ϫ/0) level has been determined as 0.307 eV. The introduction of one Sb-V defect results in the removal of three free electrons in Sb-doped Ge. It is proposed that this is one of the main reasons for the fast free carrier removal and n→p conversion of the conductivity type in Ge:Sb upon electron-or gamma-irradiation at room temperature.

It is argued that the vacancy–oxygen (VO) complex (A center) in Ge has three charge states: double negative, single negative, and neutral. Corresponding energy levels are located at Ec−0.21 eV (VO−−/−) and Ev+0.27 eV (VO−/0). An absorption line at 716 cm−1 has been assigned to the asymmetrical stretching vibration mode of the doubly negatively charged VO complex.

Electrically active defects introduced into Ge crystals co-doped with tin and phosphorus atoms by irradiation with 6 MeV electrons have been studied by means of transient capacitance techniques and ab-initio density functional modeling. It is shown that Sn atoms are effective traps for vacancies (V) in the irradiated Ge:Sn+P crystals. The electronic structure of Sn-V is unraveled on the basis of hybrid states from a Sn atom and a divacancy. Unlike the case for Si, Sn-V in Ge is not a donor. A hole trap with 0.19 eV activation energy for hole emission to the valence band is assigned to an acceptor level of the Sn-V complex. The Sn-V complex anneals out upon heat-treatments in the temperature range 50-100 °C. Its disappearance is accompanied by the formation of phosphorus-vacancy centers. © 2011 American Institute of Physics

Defects induced by irradiation with fast electrons and 60Co gamma-rays in oxygen-rich Ge crystals have been studied by means of infrared absorption, deep level transient spectroscopy (DLTS) and Hall effect measurements. It is found that the vacancy -oxygen (V -O) complex in Ge has three charge states (doubly negative, singly negative and neutral ones) and two corresponding energy levels in the gap at about E c -0.21 eV and E v + 0.27 eV. Three absorption bands at 621.4, 669.1 and 716.2 cm -1 are identified as oxygen-related asymmetrical stretching vibrations for the neutral, singly negatively charged and doubly negatively charged states of the V -O complex, respectively.

The intensities of infrared absorption due to the asymmetric stretching vibrations of interstitial oxygen atoms in Ge crystals enriched with O16 and O18 isotopes have been compared with oxygen concentrations determined by means of secondary ion mass spectrometry. For Ge samples with oxygen content less than 5×1017cm−3, a good correlation has been found between the values of oxygen concentration and the values of the absorption coefficient at the maximum of the Oi16 related absorption band at 855.6cm−1 with a proportionality coefficient CO=1.05×1017cm−2.

No abstract

The occurrence of some types of configurationally bistable thermal donors with negative effective correlation energy ( U < 0 ) , that are formed a t initial stages of heat treatment at T 5 673 K of the oxygen containing germanium crystals is presented. The study of the equilibrium electron occupation function of three transforming thermal donors types enables one t o obtain the values of U and the probability of double electron occupancy. By means of the kinetics of thermal donor transformation processes between two equilibrium configurations the activation energy and the cross-section for extrinsic self-trapping of charge carriers are determined. The results obtained are discussed in terms of very large lattice relaxation phenomena.