Current transport behaviour of Au/n-GaAs Schottky diodes grown on Ge substrate with different epitaxial layer thickness over a wide temperature range

The work presents temperature dependent forward and reverse current-voltage (I-V) analyses of n-GaAs/Au Schottky Diodes grown on n+ Ge substrate with different epitaxial layer thicknesses. While some of the Schottky diodes follow TED mechanism, others exceed significantly from this theory due to existence of patches of reduced barrier height embedded in the Schottky interface. The zero bias barrier heights (φbo) increase (0.649 to 0.809 eV) while the ideality factors (η) decrease (1.514 to 1.052) with increase in epitaxial layer thickness (1-4 μm), thus, indicating similar behaviour to that observed for the I-V characteristics of the undertaken Schottky diodes with decreasing temperature. It all indicated the existence of barrier inhomogenities over the M-S interface. The breakdown behaviour analysis of these diodes showed some interesting results; the breakdown voltage (VBR) decreases with temperature and shows ‘Defect Assisted Tunneling’ phenomenon through surface or defect states in the 1 μm thick epitaxial layer Schottky diode while VBR increases with temperature in 3 μm and 4 μm thick epitaxial layer Schottky diodes which demonstrate ‘Avalanche Multiplication’ mechanism responsible for junction breakdown. The reverse breakdown voltage is also seen to increase (2.7-5.9 Volts) with the increase in epitaxial layer thickness of the diodes. The undertaken diodes have been observed to follow TFE mechanism at low temperatures (below 200 K) in which the tunneling current component increases with epitaxial layer thickness which has been ascribed as an impact of GaAs/Ge hetero-interface over the Au/n-GaAs Schottky barrier. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2788

Small Quadrupole Deformation for the Dipole Bands in 112In

High spin states in $^{112}$In were investigated using $^{100}$Mo($^{16}$O, p3n) reaction at 80 MeV. The excited level have been observed up to 5.6 MeV excitation energy and spin $\sim$ 20$\hbar$ with the level scheme showing three dipole bands. The polarization and lifetime measurements were carried out for the dipole bands. Tilted axis cranking model calculations were performed for different quasi-particle configurations of this doubly odd nucleus. Comparison of the calculations of the model with the B(M1) transition strengths of the positive and negative parity bands firmly established their configurations.Comment: 10 pages, 11 figures, 2 table

Multi-quasiparticle gamma-band structure in neutron-deficient Ce and Nd isotopes

The newly developed multi-quasiparticle triaxial projected shell-model approach is employed to study the high-spin band structures in neutron-deficient even-even Ce- and Nd-isotopes. It is observed that gamma-bands are built on each intrinsic configuration of the triaxial mean-field deformation. Due to the fact that a triaxial configuration is a superposition of several K-states, the projection from these states results in several low-lying bands originating from the same intrinsic configuration. This generalizes the well-known concept of the surface gamma-oscillation in deformed nuclei based on the ground-state to gamma-bands built on multi-quasiparticle configurations. This new feature provides an alternative explanation on the observation of two I=10 aligning states in 134Ce and both exhibiting a neutron character.Comment: 15 pages, 9 figures, accepted by Nucl. Phys.

Level structures in the

Excited states of the 49 107 In nucleus were populated through the 78Se ( 32S , p2n) fusion-evaporation reaction at beam energy, E lab = 125 MeV. The de-excitations were studied using in-beam $\gamma$ -ray spectroscopic techniques involving the Compton-suppressed clover detector array. The level scheme of 107In consisting of about seven bands is established up to spin ∼ 45/2ℏ with the addition of 25 new transitions. Spins and parities of various levels have been assigned through the DCO and polarization measurements. The level structures observed in 107In have been interpreted in the framework of a microscopic theory based on the deformed Hartree-Fock (HF) and angular-momentum projection techniques. Various bands are reproduced in band mixing calculations with the configurations involving high-$\Omega$ $\pi$ g 9/2 and $\nu$ d 5/2 orbits, and low-$\Omega$ $\pi$ g 7/2 , $\nu$ g 7/2 and $\nu$ h 11/2 orbits

Rotational structures in the

The collective band structures of the 125Cs nucleus have been investigated by in-beam γ-ray spectroscopic techniques following the 110Pd ( 19F, 4n) reaction at 75MeV. The previously known level scheme, with rotational bands built on πg 7/2, πg 9/2 and πh 11/2 orbitals, has been extended and evolves into bands involving rotationally aligned ν(h 11/2)2 and π(h 11/2)2 quasiparticles. A strongly coupled band has been reassigned a high-K πh 11/2 ⊗ νg 7/2 ⊗ νh 11/2 three-quasiparticle configuration and a new side band likely to be its chiral partner has been identified. Configurations assigned to various bands are discussed in the framework of Principal/Tilted Axis Cranking (PAC/TAC) model calculations

Band structures in Rh-99

Excited states in the Rh-99 nucleus were populated using the fusion-evaporation reaction As-75(Si-28,2p2n) at E-lab = 120 MeV and the de-excitations were investigated through in-beam gamma-ray spectroscopic techniques using the INGA spectrometer consisting of 18 clover detectors. The observed band structures are discussed in the framework of tilted axis cranking shell-model calculations. Level structures at low energies are identified as resulting from the rotational bands based on the pi p(1/2) and pi g(9/2) configurations. The Delta I = 1 coupled bands are observed at higher excitation energies and have been interpreted as based on the pi g(9/2) circle times nu g(7/2) circle times nu d(5/2), pi p(1/2) circle times nu h(11/2) circle times nu d(5/2) and pi g(9/2) circle times nu h(11/2) circle times nu g(7/2) configurations. Calculations based on cranked Nilsson- Strutinsky (CNS) formalism have been performed to interpret the favoured states with I-pi = (41/2(-), 43/2(-)) and (51/2(-), 53/2(-)) as maximal spin aligned states built on the valence space nu(d(5/2)g(7/2))(15/2)(3), (17/2)(h(11/2))(11/2)(1) configuration combined with the fully-aligned pi(g(9/2))(25/2)(5) configuration and the pi(g(9/2))(15/2)(5) configuration with one anti-aligned g(9/2) proton, respectively

Structure of nearly degenerate dipole bands in Ag

The high spin negative parity states of Ag have been investigated with the B+Mo reaction at 39 MeV beam energy using the INGA facility at TIFR, Mumbai. From the γ-γ coincidence analysis, an excited negative parity band has been established and found to be nearly degenerate with the ground state band. The spin and parity of the levels are assigned using angular correlation and polarization measurements. This pair of degenerate bands in Ag is studied using the recently developed microscopic triaxial projected shell model approach. The observed energy levels and the ratio of the electromagnetic transition probabilities of these bands in this isotope are well reproduced by the present model. Further, it is shown that the partner band has a different quasiparticle structure as compared to the yrast band. © 2013 Elsevier B.V

SPECTROSCOPY OF THE LOW-LYING STATES NEAR THE HIGH SPIN ISOMER IN Ag-108

A comprehensive study of the low-lying states of 108Ag, near the isomeric state at Ei = 110 keV with Jπ = 6+ and T1/2 = 438 y, has been presented. Spectroscopy of these states has been carried out using the reaction 100Mo(11B, 3nγ)108Ag at 39 MeV beam energy using INGA. The multipolarities and electromagnetic nature of the transitions have been assigned based on the angular correlation and polarization measurements. The experimentally identified states have been compared to the results of the Projected Hartree-Fock calculations to understand the configurations involved in these states