a-Si/SiN x multilayered light absorber for solar cell
40 alternate a-Si/SiN x multilayer are incorporated as an absorber layer in a p–i–n solar cell. The device is fabricated using hot-wire chemical vapor deposition (HWCVD) technique. The structure of the multilayer film is examined by high resolution transmission electron microscopy (HR-TEM) which shows distinct formation of alternate a-Si and SiN x layers. The a-Si and SiN x layers have thickness of ~3.5 and 4 nm, respectively. The photoluminescence (PL) of multilayer film shows bandgap energy of ~2.52 eV, is larger than that of the c-Si and a-Si. Dark and illuminated current–voltage (I–V) characterization of the ML films shows that these ML are photosensitive. In the present work, it is seen that the p–i–n structure with i-layer as ML quantum well (QW) structures show photovoltaic effect with relatively high open-circuit voltage (V OC). The increment of bandgap energy in PL and high V OC of the device is attributed to the quantum confinement effect (QCE).
Keywordsa-Si/SiNx multilayer HR-TEM I–V p–i–n Solar cell HWCVD Quantum confinement effect Quantum well Energy conversion
Authors would like to thank Dr. P. K. Narwankar, Applied Materials USA for the TEM analysis of films. Discussions for characterizations of films with Prof. S. S. Major, IIT Bombay are also overwhelmed by the authors.