Studies of Electrically and Recombination Active Centers in Undoped GaN Grown by OMVPE

1996 ◽  
Vol 449 ◽  
Author(s):  
A. Y. Polyakov ◽  
A. V. Govorkov ◽  
N. B. Smirnov ◽  
M. Shin ◽  
M. Skowronski ◽  
...  
Keyword(s):  
Band Edge ◽  
Conduction Band Edge ◽  
Thermally Stimulated Current ◽  
Active Centers ◽  
Spatially Resolved ◽  
Thermally Stimulated Current Spectroscopy ◽  
Electron Beam Induced Current ◽  
Recombination Centers ◽  
Transient Spectroscopy ◽  
Dislocation Walls

ABSTRACTDeep centers were studied in GaN samples grown by organometallic vapor phase epitaxy (OMVPE). Electron traps 0.2 eV and 0.5 eV below conduction band edge and 0.25 eV and 0.50.85 eV above the valence band edge were detected by means of deep levels transient spectroscopy (DLTS), photoelectron relaxation spectroscopy (PERS) and thermally stimulated current spectroscopy (TSC). The photoconductivity at low temperature is shown to be persistent and the magnitude of photosensitivity is dependent on the way the samples are grown. Microcathodoluminescence (MCL) and electron beam induced current (EBIC) measurements indicate that the density of deep recombination centers near the dislocation walls between the misoriented GaN domains is lower than inside the domains. Spatially resolved PERS measurements show that the concentration of the 0.85 eV level is higher in the low angle grain boundary regions that produce bright contrast in EBIC and MCL.

Deep States in GaN Studied by Thermally Stimulated Current Spectroscopy

1995 ◽  
Vol 395 ◽  
Author(s):  
Z.C. Huang ◽  
J.C. Chen ◽  
D.B. Mott
Keyword(s):  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Surface States ◽  
Chemical Vapor ◽  
Deep Levels ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Thermally Stimulated Current ◽  
Furnace Annealing ◽  
Thermally Stimulated Current Spectroscopy

ABSTRACTDeep levels in insulating GaN grown by metalorganic chemical vapor deposition have been studied using thermally stimulated current (TSC) and photocurrent (PC) spectroscopies. Five main traps were observed by TSC measurement in the as-grown undoped GaN in the range of 0-0.75 eV below the conduction band edge or above the valence band edge. Their activation energies were 0.11, 0.24, 0.36, 0.53 and 0.62 eV, respectively. PC measurements showed three deep levels located within the bandgap at 1.32, 1.70 and 2.36 eV, respectively. Furnace annealing was carried out on GaN for identifying all the observed deep levels. We have found that the 0.24, 0.36 and 0.53 eV traps were eliminated by annealing at 1000°C under N2for six hours, whereas the 0.62 eV trap density increased after annealing. The three deep levels detected by the PC measurement were not affected by annealing. The 1.70 eV trap, which is located at the midgap, does not seem to compensate with narrow donors. We attribute the 0.11 eV trap to surface states, and the 0.62 eV trap to nitrogen vacancies.

Deep Level Characterization of 5 MeV Proton Irradiated SiC PiN Diodes

2016 ◽  
Vol 858 ◽  
pp. 308-311 ◽  
Author(s):  
Giovanni Alfieri ◽  
Andrei Mihaila ◽  
Hussein M. Ayedh ◽  
Bengt Gunnar Svensson ◽  
Pavel Hazdra ◽  
...  
Keyword(s):  
Energy Range ◽  
Minority Carrier ◽  
Deep Level ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Minority Charge Carrier ◽  
Carrier Traps ◽  
Transient Spectroscopy ◽  
The Impact

In this contribution, we report on the electrical characterization of point defects in 4H-SiC p+in diodes. Ten electrically active levels have been detected in the base region of the devices, by employing Deep Level Transient Spectroscopy (DLTS) and Minority Carrier Transient Spectroscopy (MCTS). Of these ten levels, six are majority carrier traps, in the 0.1-1.7 eV energy range below the conduction band edge, and four were minority carrier traps located in the 0.13-0.4 eV energy range above the valence band edge. We found that, during DLTS measurements, both majority and minority carrier traps can be detected and we explain this by considering the behavior of the quasi-Fermi levels. At last, we studied the impact of proton irradiation on the minority charge carrier lifetime.

A Study of Deep Energy-Level Traps at the 4H-SiC/SiO2 Interface and Their Passivation by Hydrogen

2008 ◽  
Vol 600-603 ◽  
pp. 755-758 ◽  
Author(s):  
Fredrik Allerstam ◽  
Einar Ö. Sveinbjörnsson
Keyword(s):  
Energy Level ◽  
Conduction Band ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Interface Traps ◽  
Enhanced Oxidation ◽  
Transient Spectroscopy

This study is focused on characterization of deep energy-level interface traps formed during sodium enhanced oxidation of n-type Si face 4H-SiC. The traps are located 0.9 eV below the SiC conduction band edge as revealed by deep level transient spectroscopy. Furthermore these traps are passivated using post-metallization anneal at 400°C in forming gas ambient.

Deep-Level Transient Spectroscopy Characterization of Interface States in SiO2/4H-SiC Structures Close to the Conduction Band Edge

2014 ◽  
Vol 778-780 ◽  
pp. 424-427
Author(s):  
Tetsuo Hatakeyama ◽  
Mitsuru Sometani ◽  
Kenji Fukuda ◽  
Hajime Okumura ◽  
Tsunenobu Kimoto
Keyword(s):  
Electron Density ◽  
Conduction Band ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Interface States ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Capture Process ◽  
Oxide Trap ◽  
Transient Spectroscopy

Constant-capacitance deep-level transient spectroscopy was carried out to characterize in detail interface states close to the conduction band edge in SiO2/SiC structures. The measured results are summarized as follows: (1) The capture of electrons by the interface states proceeds logarithmically with time. (2) The emission of electrons accelerates slightly with increasing density of captured electrons. The oxide trap model explains the logarithmic change in capture with time but not the phenomenon of accelerated emissions. This prompted us to formulate a new model that replicates the logarithmic capture process with time. In this model, we postulated the electron density at the interface decreases exponentially as the trapped electron density increases owing to the interaction between the trapped electrons and the free electrons. In this case, the capture process is almost the same as with the oxide trap model except for the definition of parameters. Further, we do not need to take into account the delay of the emission process caused by tunneling. The phenomenon of accelerated emissions may be explained by interactions among captured electrons in this model.

Point Defects Investigation of High Energy Proton Irradiated SiC p+-i-n Diodes

2017 ◽  
Vol 897 ◽  
pp. 246-249 ◽  
Author(s):  
Giovanni Alfieri ◽  
Andrei Mihaila ◽  
Roberta Nipoti ◽  
Maurizio Puzzanghera ◽  
Giovanna Sozzi ◽  
...  
Keyword(s):  
Deep Level ◽  
Minority Carrier Lifetime ◽  
Current Mode ◽  
High Energy ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Electrical Measurements ◽  
Transient Spectroscopy ◽  
Comparison Of The Results ◽  
The Impact

We performed deep level transient spectroscopy (DLTS), in capacitance, constant-capacitance and current mode, on 5 MeV proton irradiated 4H-SiC p+-i-n diodes. The study has revealed the presence of several majority and minority traps, ranging in the 0.4-1.6 eV below the conduction band edge and in the 0.4-1.5 eV above the valence band edge. We present a comparison of the results obtained with the three modes and discuss the nature of the detected traps, in the light of previous results found in the literature. At last, the impact of the irradiation on the minority carrier lifetime is evaluated by electrical measurements.

scholarly journals Conduction Band Edge Energy Profile Probed by Hall Offset Voltage in InGaZnO Thin Films

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 822
Author(s):  
Hyo-Jun Joo ◽  
Dae-Hwan Kim ◽  
Hyun-Seok Cha ◽  
Sang-Hun Song
Keyword(s):  
Magnetic Field ◽  
Electron Density ◽  
Conduction Band ◽  
Electron System ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Offset Voltage ◽  
Three Samples ◽  
Dimensional Electron System ◽  
Longitudinal Distance

We measured and analyzed the Hall offset voltages in InGaZnO thin-film transistors. The Hall offset voltages were found to decrease monotonously as the electron densities increased. We attributed the magnitude of the offset voltage to the misalignment in the longitudinal distance between the probing points and the electron density to Fermi energy of the two-dimensional electron system, which was verified by the coincidence of the Hall voltage with the perpendicular magnetic field in the tilted magnetic field. From these results, we deduced the combined conduction band edge energy profiles from the Hall offset voltages with the electron density variations for three samples with different threshold voltages. The extracted combined conduction band edge varied by a few tens of meV over a longitudinal distance of a few tenths of µm. This result is in good agreement with the value obtained from the analysis of percolation conduction.

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