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.
Claims19
A voltage tunable solar-blind UV detector comprising:
- a vertical bipolar transistor structure;
- an upper epitaxial graphene emitter layer;
- an intermediate p-SiC epilayer;
- an n+SiC substrate layer;
- 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 voltage tunable solar-blind UV detector comprising:
- forming a vertical bipolar transistor structure;
- growing a p-SiC epilayer on an n+SiC substrate layer substrate via a CVD reactor;
- growing an epitaxial graphene top electrode layer on the p-SiC epilayer by selective etching of
- Si from SiC using a Tetrafluorosilane 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 10, wherein the CVD reactor uses dichlorosilane and propane in hydrogen ambient at 300 Ton and 1600 C.
The method of 10, wherein substantially circular graphene regions are defined using photolithography followed by O2 plasma reactive-ion etching.
The method of 16, wherein the substantially circular graphene mesa regions have a diameter of substantially 250 gm.
The method of 10, wherein the thickness of the epitaxial graphene top electrode layer is ranges from 1 monolayer to 20 monolayers.
The method of 10, wherein the voltage tunable solar-blind UV detector detects UV-C radiation, λ200-280 nm, without responding to UV radiation wherein λ>290 nm.
Dependencies are inferred from the claim text.