Remarkable room‐temperature magnetoresistance in silicon strip devices

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Figure 1

 Geometry of the Si strip devices and the corresponding 

measuring configurations of one top contact (solid line) and ten 

top contacts (dashed line). The length and width of the devices 

are 

L

 = 20 mm  and 

W

 = 5 mm.  Every  p

+

 region has a width of 

450 

μ

m and the spacing between two neighbouring p

+

 regions is 

50 

μ

m. 

 

ployed to achieve a good surface resistivity higher than 

2000 

Ω

 cm. The wafers are first cleaned with a routine 

RCA procedure. Then an oxidation layer with the thickness 

of 

∼

600 nm is grown. The micro-strip patterns are then 

photolithographically transferred to the wafers. After that, 

the wafers are further treated with boron implantation at 

40 keV for a dose of 2.0 

×

 10

14

 atoms/cm

3

 on the top sur-

face and phosphorus implantation at 60 keV for a dose of 

1.0 

×

 10

15

 atoms/cm

3

 at the bottom surface. Finally, 50 nm 

thick Al electrodes at the top and bottom are sputtered. 

Geometry of the complete Si strip devices and corre-

sponding measuring configurations are sketched in Fig. 1. 

Instead of the normally employed lateral geometry [15], a 

vertical geometry structure of Si(p

+

)/Si(n)/Si(n

+

) is adopted 

to realize a wide space-charge region. The length and 

width of the devices are 

L 

= 20 mm and 

W 

= 5 mm, respec-

tively. Every p

+

 region has a width of 450 

μ

m and the spac-

ing between the neighbouring p

+

 regions is 50 

μ

m. In this 

study, we employed two Keithley 2400 instruments, which 

serve as the voltage meter and current meter, respectively 

(see the related connection in Fig. 1). The magnetic field is 

applied along the strips and perpendicular to the current. 

Two measuring configurations are used in our experiment 

with one-top-contact and ten-top-contact, as marked in 

Fig. 1 by the solid and dashed lines, respectively. The MR 

ratio is defined as

 

{

[

R

(

H

)–

R

(0)]/

R

(0)

}

 

×

 100%, where 

R

(

H

) 

and 

R

(0) are the resistances with and without an applied 

magnetic field, respectively.