Three - University of Arkansas Physics Department

APPLIED PHYSICS LETTERS VOLUME 75, NUMBER 4
Proton irradiation effects on the intersubband transition in GaAsIAIGaAs
multiple quantum wells with bulk or si~perlattice barriers
M. 0. ~anasreh~)
Air Force Reseclrch Luh (AFRWVSSS), 3550 Aberdeen AIV,
:Vew Mexico 87117-5776
SE, Bldg 426, Kirtlawd .4FB
P. Ballet, J. B. Srnathers, and G. J. Salarno
Departrnenf of Physics, Uni~versie of Arkunsas. Fayeueville, Arkn~rsus 72701
Chennupati Jagadish
Department of Elecfronic Muferiirl.~ Engineering, Research School of Physical Scietlces utul Engineering,
Australian Matior~al Univcrsi~, Cnnbew, ACT 0200. .4ustralici
(Received 13 April 1999; accepted for publication 4 June 1999)
The optical absorption spectra, measured at either 77 or 300 K, of the intersubband transition in
Si-doped GaAslAIGaAs multiple quantum wells were studied before and after I MeV proton
irradiation. The intersubband transition in samples with superlattice barriers was conlpletely washed
out after irradiation with doses as low as 1.OX 10'%m-'. Thc total integrated areas of the
intersubband transitions were studied as a hnction of doses. Tt was observed that the intersubband
transitions in samples with superlattice barriers degradc at a fastcr ratc as compared to those
transitions in samples with bulk barriers. O 1999 American Institute of Physics.
[SOOO3-695 I (99)03730-41
Proton irradiation effect on the intersubband transitions
in 111-V semiconductor quanhim wells received little attention
thus far. The desire to study this effect is based - on
twofold. First, intersubband transitions form the basis of a
new generation of long and very long wavelength infrared
detectors.'-3 Second, space application is one of the most
recent uses of this class of detectors, hence, the su~ivability
of these detectors in space and radiation environment becomes
very important. Charge ionization and atomic displacement
are the most important effects in irradiated semiconductor
inaterials and devices. Charge ionization plays a
major role in the device perfomlance since irradiation induced
charge accun~ulation has a detriment effect on electronic
and optoclcctronic devices. Generally speaking, the
chargc ionization effect is scnsitive to the tcnlperature (Ti) at
which the irradiation is performed. On the other hand, irradiation
induced atomic displaccrnent affect both devices and
materials. It is more profound at high doses and less sensitive
to 7,.
Irradiation effects on the intersubband transitions in
GaAslAlGaAs multiple quantum wells (MQWs) and related
compounds have not been thoroughly studied. Gamma-ray
irradiation effect on the intersubband transitions in InGaAsI
AIGaAs MQWs have been reported.' Preliminary results on
the electron irradiation effects on intersubband transitions in
InGaAsIAIGaAs MQWs have been reported recently.' A recent
report6 on the proton irradiation effect on GaAs quantum
well lasers indicates that there is a wavelength shift in
the lasing spectra. However, the proton irradiation effects on
the intersubband transitions have not been reported yet. In
this letter, we report on the proton irradiation effect on optical
absorption spectra of the intersubband transitions in
"Electronic mail: manasreo@plk.af.mil
n-type GaAsIAIGaAs MQWs. It will be shown t!-i.tt thc intensity
of the intersubband transitions is drauilrrically decreased
as a function of irradiation doses. which can b~ tuplained
in tenns of trapping of the hvo-dimensionsl clccrro~ls
in the quantum wells by the irradiation indcc~~i ,(:,:,:.:+ .. r ! ~
addition, we observed that intersubband traiisi~ions i ~.
samples with superlattice barriers degrade faster than th~se
transitions in samples with bulk bamers as the irr:rdisti~n
dose is increased. .. . .
Two multiple quantum well structures used in t4ie
present study were grown by the molecular-bc;rm epitauy
technique on a semi-insulating GaAs substrate with li.5-
pm-thick GaAs buffer layer and -200-A-thick GaAs cap
layer. The structures of the two wafers are shown in Table I. .
The barriers of the wafer labeled "B" are made of live periods
~l~a~s!~aAs superlattices. While the barlies of the .
wafer labeled "A" is bulk AIGaAs. The wonl "bufk" is
used here to indicate that the barrier is not a supesi:~ttice. The
well regions were Si-doped {[Si] = 2 X IO'%II-'J. Se\ c~;l
samples were cut and irradiated with different 4osi.s of! .
MeV protons beam. The infrared absorption sI1:ctra were
recorded at the Brewster's angel of Ga.4~ (77"1 from the
nornlal using a BOMEM Fourier-transfoml interfcronietci..in ..
T.4HLE 1. Structures of the wafers used In the present ~~LI(I) 411 ~afc!,
were SI-dopcd m thc well ([SII=ZOA 101Jcm-2} The barrt~~ m.~tcr~nla ol
wafer B are made of AIGaAs/GaAs supcrlatt~ce
Wafcr
A
--
Well thickness (A) 75 105
GaAs
Barrier material AI,,Gan7As AI,,.,G>+,,,~\a G:v\s
Harrier thickness (I\) 100 ~()(...:i
Barrier period
...
MQWs period 10 SO
0003-695119917~(4)1525/31$15.00 525 0 1999 American Institu:.: of Physics
Copyright Q2001. All Rights Reserved.