HIGH PRESSURE CONFINED CHEMICAL VAPOR DEPOSITION OF ELECTRONIC METALATTICES AND SEMICONDUCTORS IN EXTREME GEOMETRIES

Restricted (Penn State Only)
Author:
Cheng, Hiu Yan
Graduate Program:
Chemistry
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
March 26, 2018
Committee Members:
  • John V Badding, Dissertation Advisor
  • John V Badding, Committee Chair
  • Miriam Arak Freedman, Committee Member
  • Benjamin James Lear, Committee Member
  • Venkatraman Gopalan, Outside Member
Keywords:
  • High Pressure
  • Chemical Vapor Deposition
  • Nanomaterials
  • Silicon
  • Germanium
  • Metalattices
Abstract:
New materials design with tunable physical properties has been the dream of many. Well-ordered nanometer-scale materials with 3-dimensional structural order could interact with electronic, magnetic and vibrational degrees of freedom of materials to engineer new properties into well developed semiconductor platforms such as silicon and germanium. The synthetic realization of such structures, which we define as metalattices with periodicity from 1 – 60 nm highlights the possibility of continuous tuning of properties. Ordered, electrically continuous 3D structural modulations of quantum confinement and interfacial physics could lead to new physical phenomena with new electrical, thermal, magnetic and acoustic responses. This dissertation focus on the synthesis of electronic metalattice structures and other functional materials using high pressure confined chemical vapor deposition (HPcCVD). The synthetic route presented here allows for control over metalattices’ periodicity, size, symmetry, chemical composition, topology and surface chemistries. The strategy used to fabricate metalattices is to deposit semiconductors such as silicon, germanium and zinc selenide into the pores of nano-templates using HPcCVD. High pressure (up to 70 MPa), allows for void free infiltration of high quality electronic grade materials into nano-pores. A series of templates, including silica colloidal crystals of different sizes, zeolites, mesoporous silica and metal-organic frameworks were examined for tuning periodicities, symmetries and sizes of metalattices. The first silicon and germanium metalattices with 14 nm, 30 nm and 60 nm were made possible with HPcCVD infiltration. A variety of characterization techniques, including Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and x-ray diffraction were used to assess the as deposited materials quality. Post processing methods were developed to remove the nano-template and prepared the sample for advanced characterization and to increase the crystallinity of the synthesized metalattices.