Heterojunction Bipolar Transistors Featuring Epitaxial ZnGeN

SPIRE PROPOSES TO DEVELOP FOR THE FIRST TIME DEPOSITION TECHNIQUES FOR CREATING THIN FILMS OF ZnGeN(2) OF HIGH CRYSTALLINE PERFECTION TO SERVE AS THE BASE IN HIGH TEMPERATURE HETEROJUNCTION TRANSISTORS. THE FINAL TRANSISTOR STRUCTURE, TO BE DEMONSTRATED IN PHASE II, WILL RELY ON GALLIUM NITRIDE (GaN) AS THE EMITTER AND COLLECTOR SECTIONS. ZnGeN(2) IS AN EXCELLENT CANDIDATE FOR SERVING AS THE TRANSISTOR BASE, BECAUSE IT HAS A SMALLER BANDGAP THAN GaN, AS DETERMINED EARLIER BY MARUSKA, THE PROPOSED PRINCIPAL INVESTIGATOR. ZnGeN(2) IS VERY CLOSELY LATTICE MATCHED TO GaN, WHICH SHOULD ALLOW PREPARATION WITH LOW DENSITIES OF DISLOCATIONS, A STRINGENT REQUIREMENT FOR KEEPING MINORITY CARRIER LIFETIMES IN THE BASE AT VERY HIGH LEVELS, A PREREQUISITE FOR HIGH GAIN. PHASE I INVESTIGATIONS WILL CENTER ON DETERMINING ADVANCED METALORGANIC CHEMICAL VAPOR DEPOSITION CONDITIONS, BASICALLY THE SUBSTRATE TEMPERATURE AND THE Zn/Ge RATIO IN THE GAS PHASE, WHICH WILL YIELD EXCELLENT QUALITY ZnGeN(2) FILMS. THESE FILMS WILLL BE CHARACTERIZED BY SEVERAL STRUCTURAL, OPTICAL, AND ELECTRICAL MEASUREMENTS, TO PROVIDE FEEDBACK FOR OPTIMIZING GROWTH PARAMETERS. IN PHASE II, CONDITIONS FOR DEPOSITING A GaN EMIITER OF HIGH CRYSTALLINE PERFECTION ONTO THE ZnGeN(2) BASE WILL BE ESTABLISHED. FABRICATION OF HETEROJUNCTION TRANSISTORS WILL BE UNDERTAKEN, AND THEIR OPERATING CHARACTERISTICS WILL BE EVALUATED. EXTENSION OF THE GROWTH TECHNOLOGY TO DEPOSITION OF THE QUATERNARY Zn(Ge(1-x)SI(x))N(2) WILL BE INVESTIGATED.