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|Title:||SOME TRANSPORT CHARACTERISTICS OF GALLIUM ARSENIDE AND ALUMINUM GALLIUM ARSENIDE|
|Keywords:||ELECTRONICS AND COMPUTER ENGINEERING;TRANSPORT CHARACTERISTICS;GALLIUM ARSENIDE;ALUMINUM GALLIUM ARSENIDE|
|Abstract:||Gallium Arsenide and Aluminum Gallium Arsenide compound semiconductors have been at the heart of developments in Microwave devices and Optoelectronics. GaAs/GaAlAs are very useful materials for manufacturing of light emitting diodes, semiconductor lasers, photodiodes, 2DEG devices etc. GaAs also forms a part of the InGaAs and GaInAsP family used for making improved PIN diodes detectors, Gunn diodes etc. It also finds applications in microwave devices like HEMTs, HBTs, MMICs. For proper functioning of the devices made on the epitaxial layer, substrate material needs to be insulated from the epitaxial layer. To obtain high quality single crystal layer, it is often desirable to obtain epitaxial layer that differ somewhat from the substrate, which is known as heteroepitaxy. This can be accomplished easily if the lattice structure and lattice constant match for the two materials. GaAs and AIGaAs serves this purpose as epitaxial layer of A1GaAs can be grown on GaAs substrate with little lattice mismatch. In present work different properties of GaAs and AIGaAs are studied. Mobility variation with temperature has been determined for GaAs considering various scattering effects like deformation potential scattering, piezoelectric scattering, optical polar scattering and ionized impurity scattering. The mobility for f valley by this analysis comes out to be 7930 cm2/V-s at room temperature. Mobility in L and X bands have been calculated and they match with the experimental value for these bands. Also the hole mobility is calculated for GaAs considering various scattering effects. If these parameters are known ff than it is very easy to select the material for various device designs and processing. The effect of compensating the crystals by changing the compensation ratio is also observed. Hall effect analysis is used to find out the Hall concentration, Hall mobility, drift mobility and the ratio of Hall mobility to drift mobility of electrons for aluminum gallium arsenide. Hall mobility differs from drift mobility by as large as a factor of —3.5 for AlGaAs depending on composition. Hall concentration obtains a minimum with x and this can be used to find the value of composition at direct-indirect crossover. Effect of donor levels on Hall mobility, Hall concentration, drift mobility, resistivity and Hall to drift mobility ratio have been studied. These donor levels result in energy loss by recombining electrons and hence effecting electron concentration of the material. Hence the material should be studied before using it in the device processing. iv|
|Research Supervisor/ Guide:||Saxena, A. K.|
|Appears in Collections:||MASTERS' DISSERTATIONS (E & C)|
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