1063-7397/04/3302- © 2004 MAIK “Nauka /Interperiodica”
Russian Microelectronics, Vol. 33, No. 2, 2004, pp. 111–115. Translated from Mikroelektronika, Vol. 33, No. 2, 2004, pp. 143–147.
Original Russian Text Copyright © 2004 by Gromov, Elesin, Polevich, Adamov, Mokerov.
The pseudomorphic high-electron-mobility transis-
tor (PHEMT) is an advanced type of ﬁeld-effect transis-
tor based on a heterostructure with large carrier mobil-
ity and high carrier drift velocity. Such transistors are
used in both analog and digital circuits. They can oper-
ate at several tens of gigahertz, being among the fastest
semiconductor devices . Previous investigations into
the gamma-ray response of PHEMTs have shown that
their parameters vary monotonically with absorbed
This paper reports an experiment on the effect of
Co gamma rays or 45-keV x-ray photons on
GaAs/(Al, Ga)As PHEMTs, whose direct-current (dc)
performance was examined against absorbed dose. The
same relationships were also measured on standard
GaAs metal–semiconductor ﬁeld-effect transistors
(MESFETs) for comparison.
Figure 1 shows the cross section of the PHEMTs
under study, which were formed by molecular-beam
epitaxy. The PHEMT gate is 0.3
m long and 65
wide. For the MESFETs the gate length and width are
1 and 50
Radiation effects were measured on normally on
and normally off PHEMTs and MESFETs.
The gamma-ray measurements employed a
source providing a dose rate of 380 rad(GaAs)/s, the
dose being varied from
In the x-ray case, we used the REIS source  gen-
erating 45-keV photons, the doses ranging from
R. The specimens were irradiated in
three runs under zero- and nonzero-bias dc conditions
as illustrated in the table for normally off PHEMTs.
RESULTS AND DISCUSSION
Figures 2 and 3 represent postirradiation drain cur-
rent as measured against dose for gamma irradiation at
low and high drain voltages, respectively, the current
being normalized by its preirradiation value.
Ionizing-Radiation Response of the GaAs/(Al, Ga)As PHEMT:
A Comparison of Gamma- and X-ray Results
D. V. Gromov*, V. V. Elesin*, S. A. Polevich*, Yu. F. Adamov**, and V. G. Mokerov**
* Specialized Electronic Systems (SPELS), Kashirskoe sh. 31, Moscow, 115409 Russia
** Institute of Radio Engineering and Electronics, Russian Academy of Sciences, ul. Mokhovaya 11, Moscow, 103907 Russia
Received April 28, 2003
—An experiment is reported on the effect of
Co gamma rays or 45-keV x-ray photons on the
GaAs/(Al, Ga)As PHEMT. It is shown that x-ray treatment can improve the dc performance of the device in
some cases. This ﬁnding is attributed in part to the annealing or modiﬁcation of DX centers.
ON ADVANCED GaAs FETs
) GaAs layer 28 nm thick
As layer 18 nm thick
As spacer 4.4 nm thick
12 nm In
100 nm GaAs buffer
Semi-insulating GaAs(001) substrate
PHEMT cross section.
18 nm thick