Date of Award


Degree Name

Doctor of Philosophy


Mechanical Engineering


Ramana V. Chintalapalle


Germanium dioxide (GeO2) is a metal oxide semiconductor with multiple polymorphs that has recently garnered a significant amount of scientific attention owing to its novel ultra-wide band gap and pseudo-capacitive properties, which can potentially transcend current power electronic, optoelectronic, and supercapacitor technologies. However, due to the difficulty in the synthesis of stable crystalline phases of individual polymorphs of GeO2 thin films, this material system demands complex and resource-intensive deposition techniques to synthesize. An attempt was made to develop cost-effective and scalable deposition techniques to stabilize specific crystalline phases of GeO2 thin films. These phases were further structurally fine-tuned to state and enhance their opto-electronic and pseudocapacitive performance. This objective is achieved by careful optimization of deposition methods based on a close feedback loop of thin film synthesis and comprehensive analysis of structural, stoichiometric, optical, and electrochemical behavior. Substrate-induced phase stabilization/texturing, thermal ad-atom activation, doping, and modulation of reactive environment during deposition are the primary parameters optimized for phase stabilization and correlation of the structure-property relationship in GeO2 thin films. In this thesis, we synthesize phase-segregated α-quartz and novel cristobalite GeO2 thin films on Silicon substrates based on a hybrid deposition protocol. Substrate-induced phase stabilization of α-quartz GeO2 on c-cut Sapphire substrates up to a temperature of 1100˚ was demonstrated. Evaluation of lattice structure and optical band gap tuning as a function of tin (Sn) incorporation into α-quartz GeO2 thin films was conducted. The novel pseudocapacitive behavior of Sn incorporated cristobalite GeO2 thin films is reported for the first time in this work. The analysis and discussion in this work are believed to be useful in a plethora of power-electronic and energy storage applications.




Recieved from ProQuest

File Size

165 p.

File Format


Rights Holder

Paul Gaurav Nalam

Available for download on Thursday, January 02, 2025