After the comparison of open circuit voltage and short circuit current, I-V curve and efficiency for the solar cell with heavy doping POCl3
diffusion and the best result of light doping POCl3 with Al2O3 passivation are shown in Fig.3.45 to Fig.3.47, Table.3.2, Table.3.3, we could clearly discover that for light doping POCl3 diffusion with Al2O3 passivation condition, the best solar cell is for 675℃ POCl3 diffusion with Al2O3
emitter passivation layer at 400℃ annealing 30 minutes in O2 ambient, which efficiency could achieve 7.37%. However, the efficiency of the solar cell with heavy doping POCl3 diffusion and Al2O3 passivation at
annealing temperature 400 ℃ could achieve 7.59%. This can be attributed to the accident during device fabrication, during the process the HF treatment before ALD Al2O3 deposition, photoresist is applied for texture surface to protect SiNx anti reflection layer and PSG passivation, the photoresist we adopted is FH-6400, the photoresist could not cover the texture surface completely during spin coating process, hence SiNx and PSG was etched by HF, the front surface after HF treatment is shown in Fig.3.48, Fig.3.49, for the following HF treatment in fabrication process, we adopted AZ-4620 for front surface protection.
1E15 2E15
Fig. 3.1 lifetime of heavy doping POCl3 diffusion
Fig. 3.2 lifetime of heavy doping POCl3 diffusion with wet oxide growing
400 500 600 700 800 0.1
1 10
heavy doping
heavy doping with wet oxide
Il lu mi n a ti on (s u n )
Fig. 3.3 implied open circuit voltage for heavy doping POCl3 diffusion w/wo wet oxide growing
Fig. 3.4 saturation current density for heavy doping POCl3 diffusion w/wo wet oxide growing
1E15 1E16
light doping with PSG with SiNx
Fig. 3.5 lifetime of light doping w/wo PSG
Fig. 3.6 SRV of light doping w/wo PSG
650 700 750 800 1
2 3 4
Il lu mi n ati on ( su n )
Implied Open Circuit Voltage (mV)
light doping with SiNx
light doping with PSG and SiNx
Fig. 3.7 implied open circuit voltage of light doping w/wo PSG
Fig. 3.8 lifetime of light doping at 650℃ on texture/polish surface
Fig. 3.9 lifetime of light doping at 675℃ on texture/polish surface
Fig. 3.10 lifetime of light doping at 650℃, 675℃, 700℃ and heavy doping 850℃
Fig. 3.11(a) saturation current for light doping with different temperature and heavy doping with wet oxide growing
Fig. 3.11(b) saturation current for light doping with different temperature and heavy doping with wet oxide growing
Fig. 3.12 interface band diagram and TEM image [3.4]
Fig. 3.13 lifetime of Al2O3 layer at different annealing temperature
Fig. 3.14 SRV of Al2O3 layer at different annealing temperature
Fig. 3.15 implied open circuit voltage of Al2O3 layer at different annealing temperature
Fig. 3.16 OM image of Al2O3 layer at 300℃ annealing
Fig. 3.17 OM image of Al2O3 layer at 400℃ annealing
Fig. 3.18 lifetime of Al2O3 at different annealing temperature with SiNx capping layer
Fig. 3.19 SRV of Al2O3 at different annealing temperature with SiNx capping layer
Fig. 3.20 implied open circuit voltage of Al2O3 at different annealing temperature with SiNx capping layer
Fig. 3.21 SRV of Al2O3 at same 300℃ temperature w/wo SiNx capping layer
Fig. 3.22 SRV of Al2O3 at same 400℃ temperature w/wo SiNx capping layer
Fig. 3.23 open circuit voltage & shunt resistance comparison for heavy doping with different wet oxide growing time
Fig. 3.25 open circuit voltage & shunt resistance comparison for light doping with different temperature, spacer 100um, annealing at 300℃
Fig. 3.24 open circuit voltage & shunt resistance comparison for light doping with different temperature, spacer 50um, annealing at 300℃
Fig. 3.26 open circuit voltage & shunt resistance comparison for light doping with different temperature, spacer 150um, annealing at 300℃
Fig. 3.27 open circuit voltage & shunt resistance comparison for light doping with different temperature, spacer 50um, annealing at 400℃
Fig. 3.28 open circuit voltage & shunt resistance comparison for light doping with different temperature, spacer 100um, annealing at 400℃
Fig. 3.29 open circuit voltage & shunt resistance comparison for light doping with different temperature, spacer 150um, annealing at 400℃
Fig. 3.30 open circuit voltage & shunt resistance comparison for annealing with different temperature, spacer 50um, POCl3 diffusion 650℃
Fig. 3.31 open circuit voltage & shunt resistance comparison for annealing with different temperature, spacer 100um, POCl3 diffusion 650℃
Fig. 3.32 open circuit voltage & shunt resistance comparison for annealing with different temperature, spacer 150um, POCl3 diffusion 650℃
Fig. 3.33 open circuit voltage & shunt resistance comparison for annealing with different temperature, spacer 50um, POCl3 diffusion 675℃
Fig. 3.34 open circuit voltage & shunt resistance comparison for annealing with different temperature, spacer 100um, POCl3 diffusion 675℃
Fig. 3.35 open circuit voltage & shunt resistance comparison for annealing with different temperature, spacer 150um, POCl3 diffusion 675℃
Fig. 3.36 open circuit voltage & shunt resistance comparison for annealing with different temperature, spacer 50um, POCl3 diffusion 700℃
Fig. 3.37 open circuit voltage & shunt resistance comparison for annealing with different temperature, spacer 100um, POCl3 diffusion 700℃
Fig. 3.38 open circuit voltage & shunt resistance comparison for annealing with different temperature, spacer 150um, POCl3 diffusion 700℃
Fig. 3.39 short circuit current & series resistance comparison for different spacer, annealing 300℃, POCl3 diffusion 650℃
Fig. 3.40 short circuit current & series resistance comparison for different spacer, annealing 300℃, POCl3 diffusion 675℃
Fig. 3.41 short circuit current & series resistance comparison for different spacer, annealing 300℃, POCl3 diffusion 700℃
Fig. 3.42 short circuit current & series resistance comparison for different spacer, annealing 400℃, POCl3 diffusion 650℃
Fig. 3.43 short circuit current & series resistance comparison for different spacer, annealing 400℃, POCl3 diffusion675℃
Fig. 3.44 short circuit current & series resistance comparison for different spacer, annealing 400℃, POCl3 diffusion700℃
Fig. 3.45 I-V curve comparison of heavy doping with different wet oxide growing time, spacer 50um
Fig. 3.46 I-V curve comparison of heavy doping w/wo Al2O3 passivation
Fig. 3.47 I-V curve comparison of light doping POCl3 diffusion at 675℃
and Al2O3 annealing at 400℃
Fig. 3.48 poor uniformity of photoresist coating on texture surface
Fig. 3.49 SiNx and PSG etched by HF treatment due to poor uniformity of photoresist at texture surface
Fig. 3.50 damage of front side of device
Sample A
Table 3.2 comparison of heavy doping device with different treatment Table 3.1 split table of device fabrication
Table 3.3 comparison of light doping POCl3 diffusion at675℃ and Al2O3
annealing at 400℃ with different spacer