RESEARCH PAPER a-Si/SiN x multilayered light absorber for solar cell A. K. Panchal • D. K. Rai • Meril Mathew • C. S. Solanki Received: 20 April 2010 / Accepted: 2 November 2010 / Published online: 20 November 2010 Ó Springer Science+Business Media B.V. 2010 Abstract 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 photolumines- cence (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) character- ization 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 rela- tively 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). Keywords a-Si/SiN x multilayer  HR-TEM  I–V  p–i–n Solar cell  HWCVD  Quantum confinement effect  Quantum well  Energy conversion Introduction For the last few years, researchers have shown great interest in 3rd generation concept based solar cells. The challenge is to reduce overall cost of a cell as well as to overcome the Shockley–Queisser limit (Green 2000). This has led researchers to look for new material and structures that can be used as light absorbing layer. The novel cell should conserve the merits of existing technology at the same time reduce the drawbacks. In pursuit of high efficiency and low cost solar cell, the Si quantum well structure is employed here. Si bandgap engineering is possible by embedding a-Si layer between two dielectric layers and controlling the thickness (Ro ¨lver et al. 2008b; Hazama et al. 1989). The quantum confinement effect due to introduction of quantum well layers in the intrinsic region is expected to increase bandgap energy and hence, increase the cell V OC (Ro ¨lver et al. 2008a). Further, I–V characteristics can be improved by passivation of defects in a-Si layers and a-Si/SiN x interface by heat treatment in forming gas. The increase in photocurrent has been correlated with a reduction in density of interface traps due to the Si/ SiO 2 interface passivation by H atoms due to annealing the device in forming gas (Stegemann et al. 2008). The p–i–n solar cell with a-Si/SiN x multilayer QW structure as an absorber layer fabri- cated by HWCVD (shown in Fig. 1a) is discussed in this article. HWCVD technique has several advanta- ges over the currently used PECVD technique for the A. K. Panchal (&)  D. K. Rai  M. Mathew  C. S. Solanki Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India e-mail: akp@eed.svnit.ac.in 123 J Nanopart Res (2011) 13:2469–2473 DOI 10.1007/s11051-010-0139-4