Remarkable room‐temperature magnetoresistance in silicon strip devices

3 Results and discussion

 

Figure 2 exhibits current 

(

I

)–voltage (

V

) curves of the Si strip devices at different 

magnetic fields with (a) one-top-contact and (b) ten-top-

contact measuring configurations. One notes that the resist-

ance increases with the magnetic field for both measuring  

 

Figure 2

 

I–V

 curves in (a) one-top-contact and (b) ten-top-

contact measuring configurations as a function of the applied volt-

age for different applied magnetic fields at room temperature. 

 

configurations. Compared to the one-top-contact case, cur-

rent in the ten-top-contact measurement is larger due to the 

more carrier transport paths. However, the MR effect is 

stronger in the one-top-contact measurement than that in 

the ten-top-contact case. It is also worth noting that the 

I–V

 

curves in Fig. 2 do not follow the Shockley equation for an 

idealized pn junction (i.e., 

I 

= 

I

s 

[exp (

qV

/

kT

) –1], 

I

s

 is the 

reverse saturation current)

 

but well fit with 

I 

∝

 

V

β

 

(

β

 is 

2.2–2.4 and 1.2–1.6 for the one-top-contact and ten-top-

contact measurements in the voltage range of 0.5–1.0 V 

and magnetic field of 0–1.2 T). It indicates that our devices 

show the characteristics of bulk Si rather than diodes after 

they turn on, which may be originally due to the wide 

weak n region for the vertical geometry structure.  

Figure 3 summarizes the MR ratio of the Si strip de-

vices with (a) one-top-contact and (b) ten-top-contact 

measuring configurations as a function of the magnetic field 

for different applied voltages. One notes that the MR ratio 

in the one-top-contact measurement shows a pronounced 

increase after 0.5 T and then starts to saturate. A 400% 

room-temperature MR ratio is realized at the applied volt-

age of 1.0 V when the magnetic field is stronger than 0.8 T.  

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Phys. Status Solidi RRL