Analysis of Deep Levels in GaAs Detector Diodes Using Impedance Spectroscopy

1993 ◽  
Vol 302 ◽  
Author(s):  
C Eiche ◽  
M Fiederle ◽  
J Weese ◽  
D Maier ◽  
D Ebling ◽  
...  

ABSTRACTImpedance or admittance spectroscopy has been shown to be a very convenient tool for the investigation of deep levels in semiconductor junctions. At constant temperature a frequency sweep is performed. After that the impedance signal is analysed by a regularization method based on Tikhonov regularization in order to obtain the thermal relaxation times of the deep levels present in the junction. The high resolution of the regularization method in comparison to conventional techniques is demonstrated using simulated data. The temperature dependence of the thermal relaxation times provides information about the properties of the deep levels such as activation energy or capture cross section. Two donor levels with activation energies dE1 =0.58 eV and dE2 =0.68 eV are observed in our detector diodes. It can be shown that the concentration of level 2 is increased after irradiation.

2015 ◽  
Vol 821-823 ◽  
pp. 403-406 ◽  
Author(s):  
Koutarou Kawahara ◽  
Hiroshi Watanabe ◽  
Naruhisa Miura ◽  
Shuhei Nakata ◽  
Satoshi Yamakawa

Shallow and deep levels in SiC significantly affect dynamic characteristics of SiC devices; larger ionization energy and/or a smaller capture cross-section of levels in the SiC bandgap lead to a larger emission time constant and slower response of carriers. Nevertheless, knowledge about those levels is very limited. In this study, we clarified the ionization energy and the capture cross section of the Al shallow acceptor in 4H-SiC in a wide range of doping concentration by preparing appropriate samples and measuring them by thermal admittance spectroscopy. Furthermore, high densities of deep levels were discovered in Al+-implanted samples, which can degrade 4H-SiC device performance without any care.


2015 ◽  
Vol 11 (2) ◽  
pp. 216-237 ◽  
Author(s):  
Rajendran Selvamani ◽  
Palaniyandi Ponnusamy

Purpose – The purpose of this paper is to study the wave propagation in a generalized piezothermoelastic rotating bar of circular cross-section using three-dimensional linear theory of elasticity. Design/methodology/approach – A mathematical model is developed to study the wave propagation in a generalized piezothermelastic rotating bar of circular cross-section by using Lord-Shulman (LS) and Green-Lindsay (GL) theory of thermoelasticity. After developing the formal solution of the mathematical model consisting of partial differential equations, the frequency equations have been derived by using the thermally insulated/isothermal and electrically shorted/charge free boundary conditions prevailing at the surface of the circular cross-sectional bar. The roots of the frequency equation are obtained by using the secant method, applicable for complex roots. Findings – In order to include the time requirement for the acceleration of the heat flow and the coupling between the temperature and strain fields, the analytical terms have been derived for the non-classical thermo-elastic theories, LS and GL theory. The computed physical quantities such as thermo-mechanical coupling, electro-mechanical coupling, frequency shift, specific loss and frequency have been presented in the form of dispersion curves. From the graphical patterns of the structure, the effect of thermal relaxation times and the rotational speed as well as the anisotropy of the of the material on the various considered wave characteristics is more significant and dominant in the flexural modes of vibration. The effect of such physical quantities provides the foundation for the construction of temperature sensors, acoustic sensor and rotating gyroscope. Originality/value – In this paper, the influence of thermal relaxation times and rotational speed on the wave number with thermo-mechanical coupling, electro-mechanical coupling, frequency shift, specific loss and frequency has been observed and are presented as dispersion curves. The effect of thermal relaxation time and rotational speed on wave number for the case of generalized piezothermoelastic material of circular cross-section was never reported in the literature. These results are new and original.


1954 ◽  
Vol 12 (4) ◽  
pp. 519-525 ◽  
Author(s):  
G. Chiarotti ◽  
G. Cristiani ◽  
L. Giulotto ◽  
G. Lanzi

2011 ◽  
Vol 464 ◽  
pp. 583-587
Author(s):  
Ying Ze Wang ◽  
Xin Nan Song

The thermal response for given micromachine with the boundary surface exposed to sudden temperature change is studied by deriving an analytical solution of the hyperbolic heat conduction equation. Using the obtained analytical expression, the temperature profiles at the outer surface and interior of the micro beam are evaluated for various thermal relaxation times. The behaviors of hyperbolic heat propagation in micro beam are analyzed and possible anomalies are discussed by comparing the thermal behaviors of Fourier heat conduction.


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