Study of Transition Region of p-Type SiO x :H as Window Layer in a-Si:Ha-Si 1 - y Ge y :H Multijunction Solar Cells

Abstract EN

We have studied the p-type hydrogenated silicon oxide ( S i O x :H) films prepared in the amorphous-to-microcrystalline transition region as a window layer in a-Si:H/a- S i 1 - y G e y :H multijunction solar cells.

By increasing the H 2 -to- S i H 4 flow ratio ( R H 2 ) from 10 to 167, the S i O x :H(p) films remained amorphous and exhibited an increased hydrogen content from 10.2% to 12.2%.

Compared to the amorphous S i O x :H(p) film prepared at low R H 2 , the S i O x :H(p) film deposited at R H 2 of 167 exhibited a higher bandgap of 2.04 eV and a higher conductivity of 1.15 × 10−5 S/cm.

With the employment of S i O x :H(p) films prepared by increasing R H 2 from 10 to 167 in a-Si:H single-junction cell, the FF improved from 65% to 70% and the efficiency increased from 7.4% to 8.7%, owing to the enhanced optoelectrical properties of S i O x :H(p) and the improved p/i interface.

However, the cell that employed S i O x :H(p) film with R H 2 over 175 degraded the p/i interface and degraded the cell performance, which were arising from the onset of crystallization in the window layer.

Compared to the cell using standard a- S i C x :H(p), the a-Si:H/a- S i 1 - y G e y :H tandem cells employing S i O x :H(p) deposited with R H 2 of 167 showed an improved efficiency from 9.3% to 10.3%, with V O C of 1.60 V, J S C of 9.3 mA/cm2, and FF of 68.9%.