Na. Hastas et al., Structural, electrical, and low-frequency-noise properties of amorphous-carbon-silicon heterojunctions, J APPL PHYS, 89(5), 2001, pp. 2832-2838
The structural, electrical, and low-frequency-noise properties of heterojun
ctions of amor- phous-carbon (a-C) films grown on either n- or p-type singl
e-crystal silicon are investigated. The a-C films were deposited by rf magn
etron sputtering at room temperature with varying the substrate bias V-b, f
rom +10 to -200 V. The study includes measurements of x-ray reflectivity (X
RR), low-frequency noise at room temperature, and dark current-voltage (I-V
) and capacitance-voltage (C-V) characteristics over a wide temperature ran
ge. Analysis of the XRR data indicates the presence of a thin SiC layer bet
ween a-C and Si, with thickness increasing up to about 1.8 nm for V-b = -20
0 V. The results show that the noise properties of the devices are independ
ent of the SiC interlayer and the a-C film deposition conditions, while the
noise of the a-C/n-Si heterojunctions is about four orders of magnitude lo
wer than that of the a-C/p-Si heterojunctions. Analysis of the I-V and C-V
data shows that the rectification properties of the a-C/n-Si heterojunction
s are governed by conventional heterojunction theory, while multistep tunne
ling is the current conduction mechanism in a-C/p-Si heterojunctions due to
a high density of interface states. (C) 2001 American Institute of Physics
.