INVESTIGATING PERFORMANCE LIMITING DEFECTS IN SILICON CARBIDE BIPOLAR JUNCTION TRANSISTORS USING ELECTRICALLY DETECTED MAGNETIC RESONANCE

Open Access
Author:
Carrier, Robert Scott
Area of Honors:
Engineering Science
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Patrick M Lenahan, Thesis Supervisor
  • Patrick M Lenahan, Honors Advisor
  • Saptarshi Das, Faculty Reader
Keywords:
  • bipolar junction transistor
  • EDMR
  • pn junctions
  • magnetometer
  • silicon carbide
  • spin dependent recombination
  • semiconductor spectroscopy
Abstract:
SiC is a wide bandgap semiconductor whose properties make it promising for use in high voltage, high temperature, high frequency, and high radiation environments where silicon devices often fail. SiC BJTs are used in military, space exploration, and aerospace applications. However, much work is needed to improve the current gain in SiC BJTs, which is limited by recombination centers throughout the defects. SDR is an EDMR technique that can identify recombination centers that directly affect device performance. Very little data is available in literature pertaining to SDR in SiC BJTs and p-n junctions. In this paper, low field SDR and near zero field magnetic resonance (NZFMR) are performed on the base-collector junction of a 4H-SiC bipolar junction transistor (BJT) in order to identify nuclear hyperfine (NHF) patterns that reveal information about performance-limiting recombination centers in the depletion regions of the BJT. The main goal of this research was to compare the NHF patterns in the low-field SDR and NZFMR measurements to each other and to hyperfine patterns in literature in order to identify performance limiting recombination centers present in the device and demonstrate the spectroscopic capabilities of low-field SDR and NZFMR, which require much less power and machinery than high-field EDMR or conventional electron paramagnetic resonance (EPR). However, no NHF patterns were undeniably identified in the four NZFMR signals or the three low-field SDR signals. The magnetometer sensitivity of the four NZFMR signals were analyzed and compared to another 4H-SiC BJT, which revealed that the SDR signals in this paper were weak. This fact partly explains why no NHF patterns could be distinguished from the noise in the signals even after long periods of signal averaging. The low-field SDR and NZFMR signals were compared which revealed an intriguing fact that the low-field and zero-field responses were of opposite polarity. The low-field SDR mechanism caused a positive change in recombination current, while the zero-field SDR mechanisms caused a negative change in recombination current. The defects responsible for the SDR responses were not identified because the NZFMR response was not yet useful without hyperfine patterns and the g values of the low-field response were not yet comparable with g values in literature. Ultimately, the spectroscopic ability of SDR on 4H-SiC BJTs was not well demonstrated.