The authors have investigated by deep level transient spectroscopy the electron traps introduced in n-type Ge during sputter deposition of Au Schottky contacts. They have compared the properties of these defects with those
introduced in the same material during high-energy electron irradiation. They found that sputter deposition introduces several
electrically active defects near the surface of Ge. All these defects have also been observed after high-energy electron irradiation.
However, the main defect introduced by electron irradiation, the V-Sb center, was not observed after sputter deposition. Annealing
at 250°C in Ar removed the defects introduced during sputter deposition.
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[Show abstract][Hide abstract] ABSTRACT: We have studied the defects introduced in n-type Ge during electron beam deposition (EBD) and sputter deposition (SD) by deep-level transient spectroscopy (DLTS) and evaluated their influence on the rectification quality of Schottky contacts by current–voltage (I–V) measurements. I–V measurements demonstrated that the quality of sputter-deposited diodes are poorer than those of diodes formed by EBD. The highest quality Schottky diodes were formed by resistive evaporation that introduced no defects in Ge. In the case of EBD of metals the main defect introduced during metallization was the V–Sb complex, also introduced during by electron irradiation. The concentrations of the EBD-induced defects depend on the metal used: metals that required a higher electron beam intensity to evaporate, e.g. Ru, resulted in larger defect concentrations than metals requiring lower electron beam intensity, e.g. Au. All the EBD-induced defects can be removed by annealing at temperatures above 325°C. Sputter deposition introduces several electrically active defects near the surface of Ge. All these defects have also been observed after high-energy electron irradiation. However, the V–Sb centre introduced by EBD was not observed after sputter deposition. Annealing at 250°C in Ar removed all the defects introduced during sputter deposition.
Full-text · Article · Oct 2008 · Materials Science in Semiconductor Processing
[Show abstract][Hide abstract] ABSTRACT: Low energy(+-80 eV) Ar plasma etching has been successfully used to etch several semiconductors, including GaAs, GaP, and InP. We have studied the only prominent defect, E0.31, introduced in n-type Sb-doped Ge during this process by deep level transient spectroscopy (DLTS). The E0.31 defect has an energy level at 0.31eV below the conduction band and an apparent capture cross-section of 1.4� x 10e�14 cm2.
The fact that no V–Sb defects and no interstitial-related defects were observed implies that the etch process did not introduce single vacancies or single interstitials. Instead it appears that higher order vacancy or interstitial clusters are introduced due to the large amount of energy deposited per unit length along the path of the Ar ions in the Ge. The E0.31 defect may therefore be related to one of these defects. DLTS depth profiling revealed the E0.31 concentration had a maximum (6�x10e13 /cm�3) close to the Ge surface and then it decreased more or less exponentially into the Ge. Finally, annealing at 250 C reduced the E0.31 concentration to below the DLTS detection limit.
Full-text · Article · Dec 2009 · Physica B Condensed Matter
[Show abstract][Hide abstract] ABSTRACT: We have used deep level transient spectroscopy (DLTS), and Laplace-DLTS to investigate the defects created in antimony doped germanium (Ge) by sputtering with 3keV Ar ions. Hole traps at EV+0.09eV and EV+0.31eV and an electron trap at EC−0.38eV (E-center) were observed soon after the sputtering process. Room temperature annealing of the irradiated samples over a period of a month revealed a hole trap at EV+0.26eV. Above room temperature annealing studies revealed new hole traps at EV+0.27eV, EV+0.30eV and EV+0.40eV.
No preview · Article · Dec 2009 · Physica B Condensed Matter