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Velocity of propagation in the shock-crystallization of sputtered amorphous germanium
Solid State Communications,
Vol. 13, pp. 329—331, 1973
Pergamon Press.
Printed in Great Britain
VELOCITY OF PROPAGATION IN THE SHOCK-CRYSTALLIZATION OF SPUTTERED AMORPHOUS GERMANIUM A. Mineo, A. Matsuda, T. Kurosut and M. Kikuchi Electrotechnical Laboratory, Tanashi, Tokyo, Japan (Received 29Apr11 1973 by T. Muto)
Shock-crystallization in sputtered amorphousgermanium thin films has been studied by a high speed movie technique. One hundred cm/sec has been obtainedas the velocity of propagation of the crystallization wave. This value is much smaller than that of the sound velocity and rules out the contribution of the acoustic shock-wave to this phenomenon.
RECENTLY, electrical, thermal and optical properties of amorphous germaniwn have been reported by many authors.2 Takamori eta!.1 have reported shock-crystallization of sputtered amorphous germanium films at room temperature, and mentioned that the crystal. lization wave appeared to be acoustically transmitted.
30
U
In order to investigate the mechanism of this phenomenon, we observed the propagation of crystallization wave by a high-speed-movie analysis.
~ z
Germanium thin films were r—f sputtered in argon atmosphere under a vacuum of 5 X lO3Torr. Single crystal of Ge(77mm~’,5mmt)was used as a target and cleaned micro slide glass was used as a substrate for this sputtering. Condition of this sputtering was as follows; substrate-to-target distance was 29mm, power density was 3.3W/cm2 and sputtering time was about 4 hours. Thickness of the films prepared in this condition is about 5 microns.
60
30
(311)
0 20
Figure 1 shows X-ray diffraction patterns of assputtered germanium film and the fIlm crystallized by picking, respectively. Diffractionpattern of as-sputtered film reveals broad halo pattern and picked film reveals typical crystalline structure of diamond-type. *
(220)
30 40 90 29 ANGLE (d.gr,.s)
60
FIG. X-ray diffraction as-sputtered film 1. and (B) the film afterpatterns pickedfor by (A) a needle, respective~!y.
Temporary staff.
t Present address; Tokai University, Hiratsuka, Kanagawa,
Japan.
329
Photographs as shown in Fig. 2 were taken by high speed camera (HD-500) in order to observe the pattern and the velocity of propagation wave. The time interval between the adjacent frames is 6msec.
330
SHOCK-CRYSTALLIZATION OF SPUTTERED AMORPHOUS GERMANIUM
-.
A
Vol. 13, No.3
B
E
FIG .2. Photographs of the propagation process taken by high-speed-movie camera (500 frames/second). Figure 3 shows the distance of the crystallization front from the picking point as a function of time. As shown in Fig. 3, the velocity of propagation is calculated to be 100cm/sec with good accuracy, and it does not reveal any noticeable change until the wave reaches the edge of the substrate. In a T-shaped sample, a schematic sketch of the movement of crystallization front at every 2msec is
shown in Fig. 4. It is observed from the figure that the propagation of crystallization is not influenced by a directional shock-wave from the picking point but proceeds by a domino-like energy transfer mechanism. It is concluded from the above mentioned facts that (1) the amorphous—crystalline conversion under. lies this phenomenon, (2) the velocity of the propagation is constant despite the fact that the crystallization
Vol. 13, No.3
SHOCK-CRYSTALLIZATION OF SPUTTERED AMORPHOUS GERMANIUM
40mm
.
~#•
~
V
7
FIG .4. Schematic sketch of the movement of the crystallization front at every 2msec after picked by a needle in a 1-shaped sample.
“~
00
40 TIME
(m,.c.
FIG .3. Relationship between the position of the crystallization front and time.
spreads m two dimensions, and (3) the absolute velocity is 100 cm/sec which is much lower than the sound velocity,’ which rules out the contribution of the acoustic shock-wave in this phenomenon.
REFERENCES 1. 2.
331
TAKAMORI T., MESSIER R. and ROY R.,AppL Phys. Lett. 20,201(1972). For example, WALLEY P.A. and JONSCHER A.K., Thin Solid Films, 1,367 (1967). AnapaToM ~J151 CKOpoCTHoii KIIH0CbeMKII l43Y4~H~ KpJ4CTa.nJul3aUllsl OT y~apaB H~flbIJI~HHblXaMOp4iHblX TOHKMX nJIeHKaX Ge. CKopocrb pacnpoc~pa~en~n KPl4CT~JIJ!M3~UM~ öbIJla 100 cM/ceK. 3HaMeH~1e ropa3.~oMOHbll1~ To~CKO~OCTMpacnpocTpaneHwn aKycTM4ecKHx BOJIH. $IBJIeHI4e, 11O-BM~U1MOMY, He }1M~~T CB$13b c aKycTH4ecKot~ y~apHotiBOJIHOi1.
Vol. 13, pp. 329—331, 1973
Pergamon Press.
Printed in Great Britain
VELOCITY OF PROPAGATION IN THE SHOCK-CRYSTALLIZATION OF SPUTTERED AMORPHOUS GERMANIUM A. Mineo, A. Matsuda, T. Kurosut and M. Kikuchi Electrotechnical Laboratory, Tanashi, Tokyo, Japan (Received 29Apr11 1973 by T. Muto)
Shock-crystallization in sputtered amorphousgermanium thin films has been studied by a high speed movie technique. One hundred cm/sec has been obtainedas the velocity of propagation of the crystallization wave. This value is much smaller than that of the sound velocity and rules out the contribution of the acoustic shock-wave to this phenomenon.
RECENTLY, electrical, thermal and optical properties of amorphous germaniwn have been reported by many authors.2 Takamori eta!.1 have reported shock-crystallization of sputtered amorphous germanium films at room temperature, and mentioned that the crystal. lization wave appeared to be acoustically transmitted.
30
U
In order to investigate the mechanism of this phenomenon, we observed the propagation of crystallization wave by a high-speed-movie analysis.
~ z
Germanium thin films were r—f sputtered in argon atmosphere under a vacuum of 5 X lO3Torr. Single crystal of Ge(77mm~’,5mmt)was used as a target and cleaned micro slide glass was used as a substrate for this sputtering. Condition of this sputtering was as follows; substrate-to-target distance was 29mm, power density was 3.3W/cm2 and sputtering time was about 4 hours. Thickness of the films prepared in this condition is about 5 microns.
60
30
(311)
0 20
Figure 1 shows X-ray diffraction patterns of assputtered germanium film and the fIlm crystallized by picking, respectively. Diffractionpattern of as-sputtered film reveals broad halo pattern and picked film reveals typical crystalline structure of diamond-type. *
(220)
30 40 90 29 ANGLE (d.gr,.s)
60
FIG. X-ray diffraction as-sputtered film 1. and (B) the film afterpatterns pickedfor by (A) a needle, respective~!y.
Temporary staff.
t Present address; Tokai University, Hiratsuka, Kanagawa,
Japan.
329
Photographs as shown in Fig. 2 were taken by high speed camera (HD-500) in order to observe the pattern and the velocity of propagation wave. The time interval between the adjacent frames is 6msec.
330
SHOCK-CRYSTALLIZATION OF SPUTTERED AMORPHOUS GERMANIUM
-.
A
Vol. 13, No.3
B
E
FIG .2. Photographs of the propagation process taken by high-speed-movie camera (500 frames/second). Figure 3 shows the distance of the crystallization front from the picking point as a function of time. As shown in Fig. 3, the velocity of propagation is calculated to be 100cm/sec with good accuracy, and it does not reveal any noticeable change until the wave reaches the edge of the substrate. In a T-shaped sample, a schematic sketch of the movement of crystallization front at every 2msec is
shown in Fig. 4. It is observed from the figure that the propagation of crystallization is not influenced by a directional shock-wave from the picking point but proceeds by a domino-like energy transfer mechanism. It is concluded from the above mentioned facts that (1) the amorphous—crystalline conversion under. lies this phenomenon, (2) the velocity of the propagation is constant despite the fact that the crystallization
Vol. 13, No.3
SHOCK-CRYSTALLIZATION OF SPUTTERED AMORPHOUS GERMANIUM
40mm
.
~#•
~
V
7
FIG .4. Schematic sketch of the movement of the crystallization front at every 2msec after picked by a needle in a 1-shaped sample.
“~
00
40 TIME
(m,.c.
FIG .3. Relationship between the position of the crystallization front and time.
spreads m two dimensions, and (3) the absolute velocity is 100 cm/sec which is much lower than the sound velocity,’ which rules out the contribution of the acoustic shock-wave in this phenomenon.
REFERENCES 1. 2.
331
TAKAMORI T., MESSIER R. and ROY R.,AppL Phys. Lett. 20,201(1972). For example, WALLEY P.A. and JONSCHER A.K., Thin Solid Films, 1,367 (1967). AnapaToM ~J151 CKOpoCTHoii KIIH0CbeMKII l43Y4~H~ KpJ4CTa.nJul3aUllsl OT y~apaB H~flbIJI~HHblXaMOp4iHblX TOHKMX nJIeHKaX Ge. CKopocrb pacnpoc~pa~en~n KPl4CT~JIJ!M3~UM~ öbIJla 100 cM/ceK. 3HaMeH~1e ropa3.~oMOHbll1~ To~CKO~OCTMpacnpocTpaneHwn aKycTM4ecKHx BOJIH. $IBJIeHI4e, 11O-BM~U1MOMY, He }1M~~T CB$13b c aKycTH4ecKot~ y~apHotiBOJIHOi1.