Annealing Effect of Cd + Ion-Implanted Liquid Encapsulated Czochralski-GaAs
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" Electrotechnical Laboratory, 1-1-4 Umezono, Tsukuba 305, Japan "" Science University of Tokyo, 1-3 Kagurazaka, Shinjuku, Tokyo 162,
Japan Science University of Tokyo, 2641 Yamazaki, Noda, Chiba 277-01, Japan
ABSTRACT Furnace annealing (FA) and rapid thermal annealing (RTA) were made for Cd* ion-implanted GaAs with Cd concentration, [Cd] from 1xl0 6 cm-3 to 3x10 2` cm 3 . In FA samples, Raman scattering spectra exhibited a single peak at 292 cm-' for entire [Cd] range which is LO-phonon mode from (100) GaAs. In RTA samples, LO-phonon mode is a single peak for [Cd]lxl0 cmf3 , the intensity of the LO-phonon reduces with increasing [Cd] and finally becomes one tenth of that of undoped GaAs. The LO-phonon intensity decreases with increasing [Cd] more rapidly in RTA samples than in FA ones. In RTA samples, LO-phonon is the single peak for [Cd]lx1020 cm 3 another broad peak appears at 269 cm-'. As is described later, the sample with [Cd]=3xl02 cm-3 has INA-NDI of -3x10 2 ° cm-3 . It was reported that for INA-NDI >-lxlIO 8 cm 3 , a signal due to plasmon coupled with LO phonon is observed in Raman scattering RAMAN (RT) RTA
Cd+ion-implanted0 GaAs (LEC) Annealed at 900 C for 3sec
RAMAN (RT) FA
Cd+ ion-implanted GaAs (LEC) Annealed at 850'C for 20 min
(cm")3)
cm 3x1021 TO3x10"'
Sl1021 (cm-1) 3
CO1x10'20
(CM-)
6xI (cm
10
C/)
,,,
3010"
3(cm
z 1.7xl18' (cm")
z
1xl0 ' cm-3. The extremely high electrical activation rate of order of 100% observed for lx l020 cmf3> [Cd]>lxl0'8 cm-3 can be principally ascribed to the underestimation of Cd atom
redistribution from the implantation profile due to the excess diffusion by high temperature annealing. 2
[Cd]-3x10'Cm3,
Raman (RI)
Annealed by RTA
Polarized
o 10 22
TO
Z(s.y)z
LO
0 1021 ..
. . ..
. . .. f . . ..
. . .. 0 FA
. ... !
T....... A....
208
0
--
tro
W010 I1019.
Z
:
.
.
6oo
-
oCc
ZZ
260
280
300
WAVENUMBER (cm1')
320
Fig.3 Dependence of Raman scattering spectra on polarization for [Cd]=3x l02' cm~3 . The upper and lower trace are for z(x,y)0 and z(x,x.)D configurations.
Fig.4 Net hole concentration of Cd, NA-N I, obtained by Hall-effect measurements as a function
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