Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The electronic activity of boron and phosphorus impurities in a-Si and
  a-Si:H   In amorphous materials, acceptor and donor impurities rarely dope the system
(shift the Fermi level). We find out why in a-Si:H. We report simulations on B
and P doping of a-Si:H and a-Si. We analyze the Electronic Density of States
(EDOS) with concentrations ranging from 1.6% to 12.5% of B or P in a-Si. The
results indicate that tetrahedral B and P are effective doping configurations
in a-Si, but high impurity concentrations introduce defect states. Clustered B
or P also introduced mid-gap states. For a-Si:H, we report that both B(3,1) and
P(3,1) (B or P atom bonded with three Si atoms and one H atom) are effective
doping configurations. We investigate H passivation in both cases. There exists
a "hydrogen poison range" for which H can modify the dopant configuration and
suppress doping. For B doping, nearby H prefers to stay at the bond-center of
Si-Si, leaves B four-fold and neutralizes the doping configuration; for P
doping, nearby H spoils the doping by making tetrahedral P three-fold.

31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics