| 1. |
- Asghar, M., et al.
(author)
-
Properties of dominant electron trap center in n-type SiC epilayers by means of deep level transient spectroscopy
- 2007
-
In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 101:7
-
Journal article (peer-reviewed)abstract
- Characterization of dominant electron trap in as-grown SiC epilayers has been carried out using deep level transient spectroscopy. Two electron traps E1 and Z1 at Ec-0.21 and Ec-0.61 are observed, respectively, Z1 being the dominant level. Line shape fitting, capture cross section, and insensitivity with doping concentration have revealed interesting features of Z1 center. Spatial distribution discloses that the level is generated in the vicinity of epilayers/substrate interface and the rest of the overgrown layers is defect-free. Owing to the Si-rich growth conditions, the depth profile of Z1 relates it to carbon vacancy. The alpha particle irradiation transforms Z1 level into Z 1/Z2 center involving silicon and carbon vacancies. Isochronal annealing study further strengthens the proposed origin of the debated level. © 2007 American Institute of Physics.
|
|
| 2. |
- Muniza Faraz, Sadia, et al.
(author)
-
Modeling and simulations of Pd/n-ZnO Schottky diode and its comparison with measurements
- 2009
-
In: Advanced Materials Research. - 1662-8985. ; 79-82, s. 1317-1320
-
Journal article (peer-reviewed)abstract
- Modeling of Pd/ZnO Schottky diode has been performed together with a set of simulations to investigate its behavior in current-voltage characteristics. The diode was first fabricated and then the simulations were performed to match the IV curves to investigate the possible defects and their states in the bandgap. The doping concentration measured by capacitancevoltage is 3.4 x 1017 cm-3. The Schottky diode is simulated at room temperature and the effective barrier height is determined from current voltage characteristics both by measurements and simulations and it was found to be 0.68eV. The ideality factor obtained from simulated results is 1.06-2.04 which indicates that the transport mechanism is thermionic. It was found that the recombination current in the depletion region is responsible for deviation of experimental values from the ideal thermionic model deployed by the simulator.
|
|
| 3. |
- Noor, Hadia, et al.
(author)
-
Time-delayed transformation of defects in zinc oxide layers grown along the zinc-face using a hydrothermal technique
- 2009
-
In: JOURNAL OF APPLIED PHYSICS. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 105:12, s. 123510-
-
Journal article (peer-reviewed)abstract
- A study of deep level defects in a hydrothermally grown, intrinsically n-type zinc oxide (ZnO) device has been carried out using conventional deep level transient spectroscopy (DLTS). Performed under variable measurement conditions, DLTS demonstrates two electron trap levels, E-1 (dominant) and E-2, with activation energies E-c-0.22 +/- 0.02 eV and E-c-0.47 +/- 0.05 eV, respectively. A time-delayed transformation of shallow donor defects zinc(interstitial) and vacancy(oxygen) (Zn-i-VO) into the E-1 level has been observed. While the x-ray diffraction measurements reveal that the preferred direction of ZnO growth is along the (10 (1) over bar0) plane, i.e., the (Zn-i-V-O) complex, it is assumed that the (Zn-i-V-O) complex is transformed into a zinc antisite (Zn-O) under favorable conditions. As a result, the free carrier concentration decreases with increasing trap concentration. Henceforth, the E-1 level exhibiting the increase in concentration is attributed to ZnO.
|
|
