Gallium nitride selective area growth and heteroepitaxy via PAMBE for power device applications

Using a custom PAMBE system, growth of GaN is explored on different substrates for vertical power device applications. Undoped and doped films are grown in different conditions and characterized via SEM, XRD, and TEM. Devices are fabricated to test novel methods and structures via I-V and C-V analysis. SAG as a method of selective area processing is developed from a method for producing thin contact layers into SNS-SAG, a technique suitable for power device geometries. Comparisons to conventional methods are made, showing an improvement of four orders of magnitude in leakage current over an ICP-RIE produced device. Thermal stress was optimized via adjustment of the mask PECVD deposition conditions and addition of a backside layer. Improvement was verified via Raman spectroscopy mapping. Novel edge termination schemes are explored via theoretical analysis and growth simulation. Application to preliminary devices is presented and routes towards improvement are outlined. Nitridation of (-201)-oriented β-Ga2O3 was investigated for the purpose of enabling GaN heteroepitaxy. Conversion of Ga2O3 to GaN was confirmed via XRD and RHEED, and layers were characterized via TEM, XRR, and AFM. Optimization allowed for growth of high quality UID GaN films as quantified by XRD rocking curves, and a model for misfit strain relief is discussed. Defect analysis is carried out via advanced x-ray and TEM methods to determine mechanisms of defect structure formation, as well as validate proposed models. Undoped films are analyzed to verify the impact of defects on leakage conduction. p-n diodes are grown and fabricated with record rectification for the p-GaN/n-Ga2O3 system demonstrated. Reverse bias carrier transport is investigated to determine leakage mechanisms. Future work is proposed, involving improvement of SNS-SAG films to allow for full application of high-efficiency edge termination schemes. The use of growth simulation will be used to investigate new geometries such as side-by-side SAG, enabling more complex devices such as vertical transistors. Advanced buffer layer schemes for GaN-on-Ga2O3 films are proposed to improve p-n diode performance. The extension of developed nitridation methods to selective area growth on Ga2O3 is discussed with preliminary work presented.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2024

Author dc:creator

• Kelly, Frank Putnam

Contributors dc:contributor

• Kim, Kyekyoon
• Bayram, Can
• Dallesasse, John
• Lee, Minjoo L
• Zuo, Jian-Min

• Heteroepitaxy
• Characterization
• Gallium Nitride
• Pambe
• Materials Growth
• Semiconductor Processing
• Power Electronics

Statement dc:rights

• Copyright 2024 Frank Kelly

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/127397

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F127397