Voltage tunable solar blindness in TFS grown EG/SiC Schottky contact bipolar phototransistors
AssigneeUniversity of South Carolina
InventorsVenkata Surya N. Chava, MVS Chandrashekhar, Anusha Balachandran
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Abstract
A voltage tunable solar-blind UV detector using a EG/SiC heterojunction based Schottky emitter bipolar phototransistor with EG grown on p-SiC epi-layer using a chemically accelerated selective etching process of Si using TFS precursor.
Claims17
A bipolar junction transistor comprising:
- an upper epitaxial graphene emitter layer grown on a selectively etched intermediate p-SiC epilayer, wherein selective etching of the intermediate p-SiC epilayer occurs via a homoepitaxy compatible Tetra-Fluoro-Silane gas precursor;
- an n+SiC substrate layer;
- and
- the upper epitaxial graphene emitter laver, intermediate p-SiC epilayer and the n+SiC substrate layer are vertically stacked to form an:
- epitaxial graphene/SiC heterojunction-based;
- voltage tunable;
- solar-blind;
- UV detector with a peak wavelength responsivity shift from 320 nm to less than 250 nm dependent upon a bias voltage applied at the epitaxial graphene emitter layer.
A method of forming a bipolar junction transistor comprising:
- growing a p-SiC epilayer on an n+SiC substrate layer substrate via a CVD reactor;
- and
- growing an epitaxial graphene top electrode layer on the p-SiC epilayer by selective etching of Si from SiC using a Tetra-Fluoro-Silane gas precursor;
- vertically stacking the epitaxial graphene top electrode layer, intermediate p-SiC epilayer and the n+SiC substrate layer to form an:
- epitaxial graphene/SiC heterojunction-based;
- voltage tunable;
- solar-blind UV detector;
- and
- applying a bias voltage to the epitaxial graphene top electrode layer to shift a peak wavelength responsivity from 320 nm to less than 250 nm dependent upon the bias voltage applied.
The method of 9, wherein the CVD reactor uses dichlorosilane and propane in hydrogen ambient at 300 Torr and 1600 C.
The method of 9, wherein substantially circular graphene regions are defined using photolithography followed by O2 plasma reactive-ion etching.
The method of 15, wherein the substantially circular graphene mesa regions have a diameter of substantially 250 μm.
The method of 9, wherein the thickness of the EG top electrode layer is ranges from 1 monolayer to 20 monolayers.
Dependencies are inferred from the claim text.