Spiral biasing adaptor for use in Si drift detectors and Si drift detector arrays
A drift detector array, preferably a silicon drift detector (SDD) array, that uses a low current biasing adaptor is disclosed. The biasing adaptor is customizable for any desired geometry of the drift detector single cell with minimum drift time of carriers. The biasing adaptor has spiral shaped ion-implants that generate the desired voltage profile. The biasing adaptor can be processed on the same wafer as the drift detector array and only one biasing adaptor chip/side is needed for one drift detector array to generate the voltage profiles on the front side and back side of the detector array.
1. A method of detecting radiation, comprising,
detecting radiation by an array of drift detector cells;
reducing overheating and power consumption of the drift detector array during the detection by connecting the drift detector array to a spiral biasing adaptor (SBA) configured to function as a voltage divider.
2. The method of claim 1 , wherein a design of the spiral biasing adaptor (SBA) satisfies the equation
ρ s Iαr=E ( r ) W ( r ) p ( r )
where ρ s is an implant sheet resistance, I is a current, αr is a length of each turn of the spiral, E(r) is a surface electric field at a radius r, W(r) is a spiral width of a spiral arm at radius r, and p(r) is a spiral pitch at radius r.
3. A drift detector comprising a Si drift detector (SDD) cell connected to a spiral biasing adaptor (SBA) configured to function as a voltage divider wherein a design of the spiral biasing adaptor satisfies the equation
ρ s Iαr=E ( r ) W ( r ) p ( r )
wherein ρ s is an implant sheet resistance, I is a current, αr is a length of each turn of the spiral, E(r)is a surface electric field at a radius r, W(r) is a spiral width of a spiral arm at radius r, and p(r) is a spiral pitch at radius r, wherein the spiral pitch and the spiral width can both change with the radius, wherein the drift detector has a front side and a back side with a first electric field potential to the front side and a second electric field applied to the back side, wherein a negative electrical potential of a spiral in the SBA satisfies equation:
φ
(
r
)
=
∫
r
1
r
2
π
ⅆ
r
p
(
r
)
for a given spiral pitch p(r) at radius r, wherein the width of a spiral of the SBA satisfies equation:
W
(
r
)
=
ρ
s
Iar
E
(
r
)
p
(
r
)
wherein the electric field E(r) on the front side of the SBA and the SDD cell is defined by
E
(
r
)
=
2
V
fd
E
dr
,
r
(
1
-
γ
)
2
[
(
1
-
γ
)
V
B
+
(
1
+
γ
)
V
fd
(
1
-
γ
)
2
-
V
E
1
]
2
-
4
V
fd
E
dr
,
r
(
r
-
r
1
)
(
1
-
γ
)
2
,
where
V
fd
is
qN
D
d
2
2
ɛ
0
ɛ
,
where E dr,r is drift field, V B is 0<V B <V fd , r is r 1 <r<R, r 1 is 0<r 1 <500 μm, and γ is 0 ≦γ≦1, wherein the potential on the backside of the SBA and the SDD cell is defined by,
Ψ(r) =|V B |+γΦ(r) (0≦γ≦1)
with a separate SBA.