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Quantum well state of cubic inclusions in hexagonal silicon carbide studied with ballistic electron emission microscopy

Ding, Yi
http://rave.ohiolink.edu/etdc/view?acc_num=osu1086207334

Abstract Details

2004, Doctor of Philosophy, Ohio State University, Physics.
SiC is a polytypic material that may crystallize in many different close-packing sequences with cubic, hexagonal, or rhombohedral Bravais lattices. All SiC polytypes have wide bandgaps ranging from 2.39 eV in cubic SiC to 3.023 – 3.330 eV in common hexagonal polytypes. This, as well as many other properties favorable to electrical applications, makes SiC a very promising material in electronic device fabrication. However, the many lattice stacking sequences may impair the stability of SiC devices. In the hexagonal 4H polytype, it has been found that thin cubic SiC inclusions may be formed due to stacking fault expansion, and it has been proposed that the inclusions may behave as quantum wells because of the lower bandgap of cubic SiC. We performed ultra-high vacuum ballistic electron emission microscopy (BEEM) measurements on n-type 4H-SiC samples containing double-stacking-fault cubic inclusions to characterize the electrical properties of individual inclusions. Thin Pt films are deposited in ultra-high vacuum on the sample surfaces to form Schottky contacts. A Schottky barrier height of ~1.01 eV is observed over the inclusions in a background of normal 4H-SiC barrier height of 1.54 eV, which directly confirms the cubic inclusions support two-dimensional propagating quantum well states, and the 0.53 eV lowering of barrier height indicates the two-dimensional conduction band minimum is located at ~0.53 eV below the conduction band minimum of bulk 4H-SiC. We also used BEEM to study the Schottky contact between Pt and p-type 4H-SiC, and observed a second transmission channel in the BEEM spectrum that suggests a split-off valence band at ~0.11 eV below the valence band maximum. We also measured the barrier heights of p-type and n-type Schottky contacts prepared under identical conditions and the results suggest the existence of an interfacial layer. An earlier study of threading dislocations in GaN using BEEM is also described. Although threading dislocations in GaN had been generally thought to be negatively charged prior to our study, our high-resolution BEEM measurements yielded no evidence of significant charge along the dislocations near the interface between Pt films and our molecular beam epitaxy grown GaN sample.
Jonathan Pelz (Advisor)
150 p.
Physics, Condensed Matter
SiC; GaN; polytypism; inclusion; stacking fault; quantum well; ballistic electron emission microscopy; Schottky barrier; threading dislocation

Recommended Citations

Citations

  • Ding, Y. (2004). Quantum well state of cubic inclusions in hexagonal silicon carbide studied with ballistic electron emission microscopy [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1086207334

    APA Style (7th edition)

  • Ding, Yi. Quantum well state of cubic inclusions in hexagonal silicon carbide studied with ballistic electron emission microscopy. 2004. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1086207334.

    MLA Style (8th edition)

  • Ding, Yi. "Quantum well state of cubic inclusions in hexagonal silicon carbide studied with ballistic electron emission microscopy." Doctoral dissertation, Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1086207334

    Chicago Manual of Style (17th edition)

osu1086207334
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© 2004, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.
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