Details
| Original language | English |
|---|---|
| Pages (from-to) | 339-345 |
| Number of pages | 7 |
| Journal | Solar Energy Materials and Solar Cells |
| Volume | 120 |
| Issue number | PART A |
| Publication status | Published - 2014 |
| Externally published | Yes |
Abstract
We investigate the thermal stability of silicon surface passivation provided by aluminium oxide (Al2O3) films deposited using atmospheric pressure chemical vapour deposition (APCVD) and fired in a belt furnace at a peak temperature of ~810 C. Firing stability is investigated for p- and n-type substrates as a function of Al2O3 film thickness both with and without a plasma-enhanced chemical vapour deposition (PECVD) SiNx capping layer, and for boron-diffused surfaces with a ~10 nm Al2O3 film only. Excellent thermal stability of the passivation is demonstrated, with effective carrier lifetimes in n-type silicon wafers remaining stable or even improving after firing, and lifetimes in p-type wafers initially degrading slightly but recovering to above their initial values following ~10 min illumination by a halogen lamp at ~20 mW/cm 2. Film thickness appears to be unimportant to stability, as does the presence of the capping layer. Surface recombination velocities of less than 3 cm/s for 1.35 Ω cm p-type and less than 2 cm/s for 1.2 Ω cm n-type substrates are measured after firing and illumination. The passivation of boron-diffused surfaces is also shown to improve slightly following firing, with a post-firing saturation current density of 42 fA/cm2 on a diffusion with a sheet resistance of 100 Ω/□ and surface dopant concentration of ~1.3×1019 cm-3. Capacitance-voltage (C-V) measurements show that short firing times result in an initial reduction of the interface defect density Dit and a slight increase of the negative insulator fixed charge density Qf, while longer firing results in a substantial increase in both Qf and Dit.
Keywords
- AlO, Silicon, Solar cells, Surface passivation
ASJC Scopus subject areas
- Materials Science(all)
- Electronic, Optical and Magnetic Materials
- Energy(all)
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)
- Surfaces, Coatings and Films
Sustainable Development Goals
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In: Solar Energy Materials and Solar Cells, Vol. 120, No. PART A, 2014, p. 339-345.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Thermal stability of silicon surface passivation by APCVD Al 2O3
AU - Black, Lachlan E.
AU - Allen, Thomas
AU - Cuevas, Andres
AU - McIntosh, Keith R.
AU - Veith, Boris
AU - Schmidt, Jan
PY - 2014
Y1 - 2014
N2 - We investigate the thermal stability of silicon surface passivation provided by aluminium oxide (Al2O3) films deposited using atmospheric pressure chemical vapour deposition (APCVD) and fired in a belt furnace at a peak temperature of ~810 C. Firing stability is investigated for p- and n-type substrates as a function of Al2O3 film thickness both with and without a plasma-enhanced chemical vapour deposition (PECVD) SiNx capping layer, and for boron-diffused surfaces with a ~10 nm Al2O3 film only. Excellent thermal stability of the passivation is demonstrated, with effective carrier lifetimes in n-type silicon wafers remaining stable or even improving after firing, and lifetimes in p-type wafers initially degrading slightly but recovering to above their initial values following ~10 min illumination by a halogen lamp at ~20 mW/cm 2. Film thickness appears to be unimportant to stability, as does the presence of the capping layer. Surface recombination velocities of less than 3 cm/s for 1.35 Ω cm p-type and less than 2 cm/s for 1.2 Ω cm n-type substrates are measured after firing and illumination. The passivation of boron-diffused surfaces is also shown to improve slightly following firing, with a post-firing saturation current density of 42 fA/cm2 on a diffusion with a sheet resistance of 100 Ω/□ and surface dopant concentration of ~1.3×1019 cm-3. Capacitance-voltage (C-V) measurements show that short firing times result in an initial reduction of the interface defect density Dit and a slight increase of the negative insulator fixed charge density Qf, while longer firing results in a substantial increase in both Qf and Dit.
AB - We investigate the thermal stability of silicon surface passivation provided by aluminium oxide (Al2O3) films deposited using atmospheric pressure chemical vapour deposition (APCVD) and fired in a belt furnace at a peak temperature of ~810 C. Firing stability is investigated for p- and n-type substrates as a function of Al2O3 film thickness both with and without a plasma-enhanced chemical vapour deposition (PECVD) SiNx capping layer, and for boron-diffused surfaces with a ~10 nm Al2O3 film only. Excellent thermal stability of the passivation is demonstrated, with effective carrier lifetimes in n-type silicon wafers remaining stable or even improving after firing, and lifetimes in p-type wafers initially degrading slightly but recovering to above their initial values following ~10 min illumination by a halogen lamp at ~20 mW/cm 2. Film thickness appears to be unimportant to stability, as does the presence of the capping layer. Surface recombination velocities of less than 3 cm/s for 1.35 Ω cm p-type and less than 2 cm/s for 1.2 Ω cm n-type substrates are measured after firing and illumination. The passivation of boron-diffused surfaces is also shown to improve slightly following firing, with a post-firing saturation current density of 42 fA/cm2 on a diffusion with a sheet resistance of 100 Ω/□ and surface dopant concentration of ~1.3×1019 cm-3. Capacitance-voltage (C-V) measurements show that short firing times result in an initial reduction of the interface defect density Dit and a slight increase of the negative insulator fixed charge density Qf, while longer firing results in a substantial increase in both Qf and Dit.
KW - AlO
KW - Silicon
KW - Solar cells
KW - Surface passivation
UR - http://www.scopus.com/inward/record.url?scp=84888332586&partnerID=8YFLogxK
U2 - 10.1016/j.solmat.2013.05.048
DO - 10.1016/j.solmat.2013.05.048
M3 - Article
AN - SCOPUS:84888332586
VL - 120
SP - 339
EP - 345
JO - Solar Energy Materials and Solar Cells
JF - Solar Energy Materials and Solar Cells
SN - 0927-0248
IS - PART A
ER -