Recent development of high κ dielectric oxides on (In)
GaAs
is reviewed in the fields of electronic structure and electric performance; this includes studies of (In)
GaAs
surfaces with various surface reconstructions, different orientations, and Indium contents, and of high κ/(In)
GaAs
interfaces. The oxide deposition was carried out using atomic‐layer deposition (
ALD
) and molecular beam epitaxy (
MBE
) via
ex‐situ
or
in‐situ
methods. For the former approach, the semiconductor surfaces prior to the oxide deposition were obtained via chemical, arsenic‐cap or annealing treatments. For the latter, the high k's were deposited on pristine freshly
MBE
‐grown (In)
GaAs
surfaces without any treatments. Surface being treated or not clearly determines the quality of the oxide interface which delivers different interfacial electronic structure and electric performance. Without exception, the
ex‐situ
treated samples show remnant native oxides, which are never found in the
in‐situ
samples. The electronic structure has been investigated using photoemission measurements, in which the photon energy was provided by
X
‐ray and synchrotron radiation. The discussion on high κ/(In)
GaAs
interfaces has been further extended to the electrical characterization including extraction of interfacial trap densities (
D
it
's). Especially, the distinct electrical characteristics of the In
0.2
Ga
0.8
As metal‐oxide‐semiconductor capacitors (
MOSCAPs
) using
MBE
‐
Ga
2
O
3
(
Gd
2
O
3
) and
ALD
‐
Al
2
O
3
as the gate are elucidated. Finally, a summary and bench‐marking of the recent advances on enhancement mode
III
‐
V
(In)
GaAs
MOSFETs
is given, which reveals the great potential of inversion‐channel (In)
GaAs
MOSFETs
for ultimate complementary
MOS
(
CMOS
) applications.
