Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scaling and the Metal-Insulator Transition in Si/SiGe Quantum Wells   The existence of a metal-insulator transition at zero magnetic field in two-
dimensional electron systems has recently been confirmed in high mobility
Si-MOSFETs. In this work, the temperature dependence of the resistivity of
gated Si/SiGe/Si quantum well structures has revealed a similar metal-
insulator transition as a function of carrier density at zero magnetic field.
  We also report evidence for a Coulomb gap in the temperature dependence of
the resistivity of the dilute 2D hole gas confined in a SiGe quantum well.
  In addition, the resistivity in the insulating phase scales with a single
parameter, and is sample independent. These results are consistent with the
occurrence of a metal-insulator transition at zero magnetic field in SiGe
square quantum wells driven by strong hole-hole interactions.

2
The categories of this paper are: math
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an