Acquisition of Single and Double Crystal X-Ray Topography System
Abstract
The Durip Award was used to purchase two pieces of instrumentation in support of one overreaching goal of the AFOSR-funded program: correlation of growth conditions of silicon carbide boules and their structural characteristics. The x-ray topography unit was ordered in September of 2000 and manufactured and delivered to Carnegie Mellon University in January of 2001. The installation was completed in March 2001 and was followed by extensive alignment and testing. The system is producing valuable data for several federally funded projects, including "Growth of Semi-insulating 6H-SiC Crystals for GaN-based Microwave Devices," funded by the Air Force Research Laboratory (AFRL); "Structural Defects in Semi-insulating SiC Wafers," funded by the Air Force Office of Scientific Research; "High Volume, High Quality Silicon Carbide Substrate Merchant Manufacturing," a subcontract to Sterling Semiconductor, Inc. from the AFRL; and "Identification of Screw Dislocation Sources in SiC PVT Growth," funded by the Office of Naval Research. The system is intensively used for imaging extended defects in silicon carbide crystals grown by the Physical Vapor Transport method and in silicon carbide high-voltage diodes. Among the major findings accomplished with the help of x-ray topography are as follows: evidence of plastic deformation occurring during crystal growth of SiC boules, which causes the dislocation multiplication and resulting densities in the 10 (super 5) sq cm range; evidence of dislocation serving as nucleation sites for stacking faults under forward bias, which leads to the degradation of SiC bipolar devices through the increase of forward voltage drop (both the stacking faults and pre-existing dislocations have been imaged using x-ray topography); and evidence of stacking faults formation during the initial stages of SiC growth leading to nucleation of screw dislocations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2001
- Accession Number
- ADA418122
Entities
People
- M. Skowronski
Organizations
- Carnegie Mellon University