Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Broad Band Single Germanium Nanowire Photodetectors with Surface Oxide
  Controlled High Optical Gain   We have investigated photoconductive properties of single Germanium
Nanowires(NWs)of diameter less than 100 nm in the spectral range of 300 to 1100
nm showing ultra large peak Responsivity in excess of 10^{7}AW^{-1}.The NWs
were grown by Vapor Liquid Solid method using Au nanoparticle as catalyst. In
this report we discuss the likely origin of the ultra large responsivity that
may arise from a combination of various physical effects which are a): Ge and
GeO_{x} interface states which act as scavengers of electrons from the
photo-generated pairs,leaving the holes free to reach the electrodes,b)
Schottky barrier at the metal and NW interface which gets lowered substantially
due to carrier diffusion in contact region and (c) photodetector length being
small (approximately few {\mu}m), negligible loss of photogenerated carriers
due to recombination at defect sites. We have observed from power dependence of
the optical gain that the gain is controlled by trap states. We find that the
surface of the nanowire has presence of a thin layer of GeO_{x} (as evidenced
from HRTEM study) which provide interface states. It is observed that these
state play a crucial role to provide a radial field for separation of
photogenerated electron and hole pair which in turn leads to very high
effective photoconductive gain that reaches a very high at low illumination
density.

33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph