Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Single-hole transistor in p-type GaAs/AlGaAs heterostructures   A single-hole transistor is patterned in a p-type, C-doped GaAs/AlGaAs
heterostructure by AFM oxidation lithography. Clear Coulomb blockade resonances
have been observed at T=300 mK. A charging energy of ~ 1.5 meV is extracted
from Coulomb diamond measurements, in agreement with the lithographic
dimensions of the dot. The absence of excited states in Coulomb diamond
measurements, as well as the temperature dependence of Coulomb peak heights
indicate that the dot is in the multi-level transport regime. Fluctuations in
peak spacings larger than the estimated mean single-particle level spacing are
observed.

27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol