Unexpected properties of the inductively coupled plasma induced defect in germanium

Inductively coupled plasma (ICP) etching of germanium introduces a single defect, the E0.31 electron trap, for a large range of argon partial pressures from 4 × 10-3 to 6.5 × 10-4mbar that correspond to ion energies of 8 to 60 eV. Ge of three crystallographic orientations, (100), (110) and (111), treated with 20 and 60 eV ICP had defect concentration profiles that were similar in appearance, with a maximum concentration of 1014 cm-3 extending more than a μm into the material, approximately three orders of magnitude deeper than what TRIM simulations predicted. All profiles were measured using Laplace deep level transient spectroscopy (L-DLTS), a technique that is sensitive to defect concentrations as low as 1011 cm-3. Isochronal annealing of samples showed concentration curves broadening after a 400 K anneal and decreasing to the 1013 cm-3 level after a 450 K anneal. Unannealed samples measured after a year exhibited similar decreases in defect concentration without broadening of their profiles. A 550 K anneal lowered the defect concentration to levels below the L-DLTS detection limit. Thereafter additional plasma treatment of the surface failed to reintroduce this defect indicating that the structure required for the formation of E0.31 was no longer present in the region under observation.http://www.elsevier.com/locate/physbhb201

Electronic properties of shallow level defects in ZnO grown by pulsed laser deposition

We have used deep level transient spectroscopy (DLTS) to characterise four defects with shallow levels in ZnO grown by pulsed laser deposition (PLD). These defects all have DLTS peaks below 100 K. From DLTS measurements and Arrhenius plots we have calculated the energy levels of these defects as 31 meV, 64 meV, 100 meV and 140 meV, respectively, below the conduction band. The 100 meV defect displayed metastable behaviour: Annealing under reverse bias at temperatures of above 130 K introduced it while annealing under zero bias above 110 K removed it. The 64 meV and 140 meV defects exhibited a strong electric field assisted emission, indicating that they may be donors

Electronic properties of shallow level defects in ZnO grown by pulsed laser deposition

We have used deep level transient spectroscopy (DLTS) to characterise four defects with shallow levels in ZnO grown by pulsed laser deposition (PLD). These defects all have DLTS peaks below 100 K. From DLTS measurements and Arrhenius plots we have calculated the energy levels of these defects as 31 meV, 64 meV, 100 meV and 140 meV, respectively, below the conduction band. The 100 meV defect displayed metastable behaviour: Annealing under reverse bias at temperatures of above 130 K introduced it while annealing under zero bias above 110 K removed it. The 64 meV and 140 meV defects exhibited a strong electric field assisted emission, indicating that they may be donors

Electronic properties and transformation kinetics of two prominent metastable defects introduced in GaAs during sputter deposition of Au Schottky contacts

Please read abstract in the article.The National Research Foundation of South Africahttp://www.elsevier.com/locate/mssp2020-08-15hj2020Physic

Observation of low-temperature annealing of a primary defect in gallium nitride

Primary defects were introduced into n-type gallium nitride (GaN) thin films by 1.6 MeV-proton bombardment at 20 K. The electronic states of these defects were investigated by means of optical space charge spectroscopy. An until now unreported primary defect, HP1, with an electronic state close to the valence band edge was detected. HP1 can be photo-ionised with photon energies of 3.4 eV. It was found to be stable up to 235 K but anneals quickly at temperatures above 240 K.National Research Foundation (NRF)http://www.elsevier.com/locate/physbhb201

Electrical characterization of metastable defects introduced in GaN by eu-ion implantation

Gallium nitride (GaN), grown by HVPE, was implanted with 300 keV Eu ions and then annealed at 1000 oC . Deep level transient spectroscopy (DLTS) and Laplace DLTS (L-DLTS) were used to characterise the ion implantation induced defects in GaN. Two of the implantation induced defects, E1 and E2, with DLTS peaks in the 100 – 200 K temperature range, had DLTS signals that could be studied with L-DLTS. We show that these two defects, with energy levels of 0.18 eV and 0.27 eV below the conduction band, respectively, are two configurations of a metastable defect. These two defect states can be reproducibly removed and re-introduced by changing the pulse, bias and temperature conditions, and the transformation processes follow first order kinetics.The South African National Research Foundation, the Fund for Scientific Research, Flanders (FWO), the Concerted Action of the KULeuven (GOA/2009/006), the Inter-university Attraction Pole (IAP P6/42) and the Center of Excellence Programme (INPAC EF/05/005).http://www.ttp.net/0255-5476.htmlhb2016Physic

Inductively coupled plasma induced deep levels in epitaxial n-GaAs

The electronic properties of defects introduced by low energy inductively coupled Ar plasma etching of n-type (Sidoped)GaAs were investigated by deep level transient spectroscopy (DLTS) and Laplace DLTS. Several prominent electron traps (Ec—0.046 eV, Ec—0.186 eV, Ec—0.314 eV. Ec—0.528 eV and Ec—0.605 eV) were detected.The metastable defect Ec—0.046eV having a trap signature similar to E1 is observed for the first time. Ec—0.314eV and Ec—0.605 eV are metastable and appear to be similar to the M3 and M4 defects present in dc H-plasma exposed GaAs.South African National Research Foundationhttp://www.elsevier.com/locate/physbnf201

The influence of high energy electron irradiation on the Schottky barrier height and the Richardson constant of Ni/4H-SiC Schottky diodes

Please read abstract in the article.National Research Foundation (NRF) of South African (Grant specific unique reference number (UID) 78838).http://www.elsevier.com/locate/mssp2016-11-30hb201

The effects of high-energy proton irradiation on the electrical characteristics of Au/Ni/4H-SiC Schottky barrier diodes

Please read abstract in the article.The University of Pretoria and the National Research Foundation (NRF) of South Africa, Grant number 98961.http://www.elsevier.com/locate/nimb2018-10-15hj2017Physic

Effects of 5.4 MeV alpha-particle irradiation on the electrical properties of nickel Schottky diodes on 4H-SiC

Current–voltage, capacitance–voltage and conventional deep level transient spectroscopy at temperature ranges from 40 to 300 K have been employed to study the influence of alpha-particle irradiation from an 241Am source on Ni/4H–SiC Schottky contacts. The nickel Schottky barrier diodes were resistively evaporated on n-type 4H–SiC samples of doping density of 7.1 1015 cm 3. It was observed that radiation damage caused an increase in ideality factors of the samples from 1.04 to 1.07, an increase in Schottky barrier height from 1.25 to 1.31 eV, an increase in series resistance from 48 to 270 X but a decrease in saturation current density from 55 to 9 10 12Am 2 from I–V plots at 300 K. The free carrier concentration of the sample decreased slightly after irradiation. Conventional DLTS showed peaks due to four deep levels for as-grown and five deep levels after irradiation. The Richardson constant, as determined from a modified Richardson plot assuming a Gaussian distribution of barrier heights for the as-grown and irradiated samples were 133 and 151 A cm 2 K 2, respectively. These values are similar to literature values.National Research Foundation (NRF) of South African (Grant specific unique reference number (UID) 78838).http://www.elsevier.com/locate/nimb2016-12-31hb201