Date of Award

2021-05-01

Degree Name

Doctor of Philosophy

Department

Mechanical Engineering

Advisor(s)

Ramana Chintalapalle

Abstract

A comprehensive investigation performed in order to understand the fundamental aspects of transition metal (TM) incorporation into Ga2O3, a wide band gap semiconductor with a huge potential for application in electronics, optics, micromechanics and optoelectronics. An approach is presented to tailor the structural, optical, electrical, mechanical properties of Ga2O3 ceramics and thin films. The tungsten (W) mixed Ga2O3 with variable W at% (Ga2-2xWxO3 ; 0.00 ≤ x ≤ 0.30) were synthesized by the high temperature solid state route involving a 2-step calcination process. The solubility limits and phase stability of the compounds are established. While solubility and phase stability occur for x ≤ 0.10 at%, additional TM-content alters the morphology from rod-shape to spherical shape with undissolved TM giving the researchers a scope to alter properties with the inclusions. A bandgap variation is also observed at higher concentrations of TM in the system giving rise to either a single edge absorption in case of WO3 and double edge absorption in case of TiO2. In both case for the TM inclusion, a red shift is observed in the band gap giving an interesting platform to approach device fabrication for optical materials.

This work also demonstrates an approach towards the practical application of Ga2O3 materials in the form thin films. The strength of thin films deposited using the pulsed laser deposition (PLD) unit is also reported. The depositions were done at higher temperature and an attempt was made to study the optical property variation with the deposition temperature. This direction was taken in this current work to study how the materials will behave at extreme temperatures if the devices were used in harsh environment. The hardness of the thin films improved with the temperature due to the high temperature kinetics which also improved the grain size giving a compact system at 700 ℃. An attempt has been made to establish the structure-property correlation, which may be useful for practical applications of Ga2O3 PLD thin films.

Language

en

Provenance

Recieved from ProQuest

File Size

133 p.

File Format

application/pdf

Rights Holder

Vishal Bhimrao Zade

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