Activation energy of hydrogen desorption from high-performance titanium oxide carrier-selective contacts with silicon oxide interlayers

The impact of hydrogen desorption on the electrical properties of TiO_x on crystalline silicon (c-Si) with SiO_y interlayers is studied for the development of high-performance TiO_x carrier-selective contacts. Compared with the TiO_x/c-Si heterocontacts, a lower surface recombination velocity of 9.6 cm/s and lower contact resistivity of 7.1 mΩ cm² are obtained by using SiO_y interlayers formed by mixture (often called SC2). The hydrogen desorption peaks arising from silicon dihydride (α1) and silicon monohydride (α2) on the c-Si surface of the as-deposited samples are observed. The α1 peak pressure of as-deposited heterocontacts with SiO_x interlayers is lower than that of heterocontacts without a SiO_y interlayer. Furthermore, the hydrogen desorption energies are found to be 1.76 and 2.13 eV for the TiO_x/c-Si and TiO_x/SC2-SiO_y/c-Si heterocontacts, respectively. Therefore, the excellent passivation of the TiO_x/SC2-SiO_y/c-Si heterocontacts is ascribed to the relatively high rupture energy of bonding between Si and H atoms.