Amplification using ambipolar hall effect in graphene

Patent metadata

Field	Value
Publication number	US-11415643-B2
Application number	US-201916657281-A
Country	US
Kind code	B2
Filing date	Oct 18, 2019
Priority date	Dec 6, 2018
Publication date	Aug 16, 2022
Grant date	Aug 16, 2022

Abstract

An amplifier includes a graphene Hall sensor (GHS). The GHS includes a graphene layer formed above a substrate, a dielectric structure formed above a channel portion of the graphene layer, and a conductive gate structure formed above at least a portion of the dielectric structure above the channel portion of the graphene layer for applying a gate voltage. The GHS also includes first and second conductive excitation contact structures coupled with corresponding first and second excitation portions of the graphene layer for applying at least one of the following to the channel portion of the graphene layer: a bias voltage; and a bias current. The GHS further includes first and second conductive sense contact structures coupled with corresponding first and second sense portions of the graphene layer. The amplifier also includes a current sense amplifier (CSA) coupled to the GHS. The CSA senses current output from the GHS.

First claim

What is claimed is:

1. An amplifier, comprising:
a graphene Hall sensor (GHS), wherein the GHS comprises:
a graphene layer formed above a substrate;
a dielectric structure formed above a channel portion of the graphene layer;
a conductive gate structure formed above at least a portion of the dielectric structure above the channel portion of the graphene layer for applying a gate voltage;
first and second conductive excitation contact structures coupled with corresponding first and second excitation portions of the graphene layer for applying at least one of the following to the channel portion of the graphene layer: a bias voltage; and a bias current; and
first and second conductive sense contact structures coupled with corresponding first and second sense portions of the graphene layer;

a current sense amplifier (CSA) coupled to the GHS, wherein the CSA senses current output from the GHS, and wherein an output of the CSA corresponds to an amplification of the applied gate voltage; and
a bias magnetic source for applying a bias magnetic field to the GHS;

wherein an amplification based on the applied gate voltage and the CSA output that results using the amplifier is expressed by the following equation:

A
V

=

μ
⁢

⁢

WC
R

⁢

BV
bias

⁢

L
⁢

(

qn
0

)

2

+

(

C
Q

⁢

V
T

)

2

where:
A v is the amplification limit;
μ is the mobility of the graphene layer;
W is the width of the excitation portions of the graphene layer;
L is the width of the graphene layer including both excitations portions;
C R is the series capacitance;
B is the bias magnetic field;
V bias is the bias voltage;
q is the electron charge;
n o is the residual charge density;
C Q is the quantum capacitance; and
V T is the constant temperature voltage.

2. The amplifier of claim 1 , wherein the bias magnetic field is a constant bias magnetic field such that an amplification factor corresponding to the amplification of the applied gate voltage is constant.

3. The amplifier of claim 1 , wherein the CSA is coupled to the GHS via the first and second conductive sense contact structures.

4. The amplifier of claim 1 , wherein the first and second conductive sense contact structures and the corresponding first and second sense portions of the graphene layer are each smaller than the first and second conductive excitation contact structures and the corresponding first and second excitation portions of the graphene layer.

5. An amplifier, comprising:
a graphene Hall sensor (GHS), wherein the GHS comprises:
a graphene layer formed above a substrate;
a dielectric structure formed above a channel portion of the graphene layer;
a conductive gate structure formed above at least a portion of the dielectric structure above the channel portion of the graphene layer for applying a gate voltage;
first and second conductive excitation contact structures coupled with corresponding first and second excitation portions of the graphene layer for applying at least one of the following to the channel portion of the graphene layer: a bias voltage; and a bias current; and
first and second conductive sense contact structures coupled with corresponding first and second sense portions of the graphene layer;

a current sense amplifier (CSA) coupled to the GHS, wherein the CSA senses current output from the GHS, and wherein an output of the CSA corresponds to an amplification of the applied gate voltage; and
a bias magnetic source for applying a bias magnetic field to the GHS;

wherein a transconductance based on a conversion of the applied gate voltage to the CSA output that results using the amplifier is expressed by the following equation:

G
m

=

A
V

R
out

<

μ
2

⁢

C
R

⁢

BV
T

where:
G m is the maximum transconductance limit;
A v is the amplification limit;
R out is the output resistance;
μ is the mobility of the graphene layer;
C R is the series capacitance;
B is the bias magnetic field; and
V T is the constant temperature voltage.

6. A method, comprising:
employing a graphene Hall sensor (GHS), wherein the GHS comprises:
a graphene layer formed above a substrate;
a dielectric structure formed above a channel portion of the graphene layer;
a conductive gate structure formed above at least a portion of the dielectric structure above the channel portion of the graphene layer;
first and second conductive excitation contact structures coupled with corresponding first and second excitation portions of the graphene layer; and
first and second conductive sense contact structures coupled with corresponding first and second sense portions of the graphene layer;

applying a gate voltage to the conductive gate structure;
applying at least one of a bias voltage and a bias current to the channel portion of the graphene layer via the first and second conductive excitation contact structures; and
sensing current output from the GHS using a current sense amplifier (CSA) coupled to the GHS, wherein an output of the CSA corresponds to an amplification of the applied gate voltage; and
applying a bias magnetic field to the GHS;
wherein an amplification based on the applied gate voltage and the CSA output that results using the employing step, the a

Assignees

• Texas Instruments Inc

Inventors

• Haroun Baher S
• Polley Arup
• Ramaswamy Srinath M

Classifications

• G01R33/07 Primary

  Hall effect devices · CPC title

• G01R15/202

  using Hall-effect devices (Hall elements in arrangements for measuring electrical power G01R21/08) · CPC title

• H03F15/00

  Amplifiers using galvano-magnetic effects not involving mechanical movement, e.g. using Hall effect · CPC title

• H01L43/065

  Electricity · mapped topic

• H01L43/04

  Electricity · mapped topic