HEMTs - Laytec
HEMTs - Laytec
HEMTs - Laytec
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Monitoring applications of EpiRAS in the growth of<br />
DHBTs and <strong>HEMTs</strong><br />
sources<br />
O. Ostinelli and C. R. Bolognesi<br />
ostin@phys.ethz.ch<br />
Eidgenössiche<br />
Technische Hochschule<br />
Zürich<br />
EpiRAS light<br />
wafer<br />
FIRST<br />
Center for Micro- and Nanoscience
Reflectance (a.u.)<br />
5.5<br />
5.0<br />
4.5<br />
4.0<br />
3.5<br />
3.0<br />
In-situ etching of InP with CBr 4<br />
InGaAs surface<br />
@1.9 eV<br />
InP<br />
growth<br />
2.5<br />
00:40 00:45 00:50 00:55 01:00 01:05 01:10 01:15 01:20<br />
pause<br />
Growth time (hh:mm)<br />
etching<br />
under<br />
CBr 4 & PH 3<br />
stop etching<br />
&<br />
cool<br />
RAS is<br />
nearly<br />
constant<br />
6<br />
4<br />
2<br />
0<br />
RAS
Composition & doping grading of GaAs x Sb 1-x :C<br />
Reflectance (a.u.)<br />
8.5<br />
8.0<br />
7.5<br />
7.0<br />
6.5<br />
6.0<br />
5.5<br />
5.0<br />
4.5<br />
4.0<br />
3.5<br />
3.0<br />
2.5<br />
InP surface<br />
@1.9 eV<br />
growth<br />
of InP<br />
stop growth<br />
& decrease<br />
T to 550°C<br />
2.0<br />
01:44 01:46 01:48 01:50 01:52 01:54 01:56<br />
Growth time (hh:mm)<br />
Ga x As 1-x Sb:C growth<br />
p (cm -3 ) x<br />
4x10 19 0.4<br />
9x10 19 0.6<br />
5 nm<br />
p (cm -3 ) x<br />
6x10 19 0.33<br />
9x10 19 0.65<br />
6<br />
4<br />
2<br />
0<br />
-2<br />
RAS
Reflectance (a.u.)<br />
Grading from In 0.53 GaAs to In 0.87 GaAs<br />
7.0<br />
6.5<br />
6.0<br />
5.5<br />
5.0<br />
4.5<br />
4.0<br />
InP surface<br />
@1.9 eV<br />
growth of<br />
In 0.53 GaAs<br />
3.5<br />
0<br />
00:10 00:11 00:12 00:13 00:14 00:15 00:16<br />
Growth time (hh:mm)<br />
In 0.53 GaAs<br />
In 0.87 GaAs<br />
In 0.53 GaAs<br />
InAs<br />
stop<br />
&<br />
cool<br />
8<br />
6<br />
4<br />
2<br />
RAS
Surface degradation during DHBT growth<br />
Reflectance (a.u.)<br />
7.0<br />
6.5<br />
6.0<br />
5.5<br />
5.0<br />
4.5<br />
4.0<br />
3.5<br />
3.0<br />
2.5<br />
2.0<br />
1.5<br />
1.0<br />
0.5<br />
@1.9 eV<br />
InGaAs:Si<br />
InP:Si<br />
1.5x10 19 cm -3<br />
GaAsSb:C<br />
InP:Si<br />
InP:Si 3.5x10 19 cm -3<br />
0.0<br />
00:00 00:10 00:20 00:30 01:20 01:30 01:40 01:50<br />
Growth time (hh:mm)<br />
InP:Si<br />
RAS signal<br />
rapidly increases<br />
surface degeneration<br />
40<br />
InGaAs:Si<br />
30<br />
20<br />
10<br />
0<br />
RAS
Surface degradation of InGaP at high Si doping<br />
Reflectance (a.u.)<br />
Reflectance (a.u.)<br />
Reflectance (a.u.)<br />
4.0<br />
3.8<br />
3.6<br />
3.4<br />
3.2<br />
0<br />
00:08 00:09 00:10 00:11<br />
4.0<br />
3.8<br />
3.6<br />
3.4<br />
Growth time (hh:mm)<br />
3.2<br />
0<br />
00:15 00:16 00:17 00:18<br />
4.0<br />
3.8<br />
3.6<br />
3.4<br />
@1.9 eV<br />
@1.9 eV<br />
@1.9 eV<br />
InGaP:Si<br />
Growth time (hh:mm)<br />
3.2<br />
0<br />
00:08 00:09 00:10 00:11<br />
Growth time (hh:mm)<br />
InGaP:Si<br />
InGaP:Si<br />
5<br />
25<br />
20<br />
15<br />
10<br />
5<br />
25<br />
20<br />
15<br />
10<br />
25<br />
20<br />
15<br />
10<br />
5<br />
RAS<br />
RAS<br />
RAS<br />
SiH 4 flux<br />
1.6x10 -3 mol/min<br />
SiH 4 flux<br />
7.8x10 -4 mol/min<br />
SiH 4 flux<br />
4.4x10 -4 mol/min<br />
n=1.7x10 19 cm -3<br />
1 μm
Conclusions<br />
EpiRAS is a basic tool for MOVPE growth<br />
MOVPE is not a black-box anymore<br />
Often the exact growth event producing surface defects can be identified<br />
Graded layers can be produced with a maximum of strain<br />
Thickness of complex/graded layers can be estimated<br />
In-situ etching with CBr 4 can be monitored & conditions adjusted for smooth surface
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