Hole-blocking titanium-oxide/silicon heterojunction and its application to photovoltaics

In contrast to the numerous reports on narrow-bandgap heterojunctions on silicon, such as strained Si1 xGex on silicon, there have been very few accounts of wide-bandgap semiconducting heterojunctions on silicon. Here, we present a wide-bandgap heterojunction—between titanium oxide and crystalline silicon—where the titanium oxide is deposited via a metal-organic chemical vapor deposition process at substrate temperatures of only 80–100 C. The deposited films are conformal and smooth at the nanometer scale. Electrically, the TiO2/Si heterojunction prevents transport of holes while allowing transport of electrons. This selective carrier blocking is used to demonstrate a low-temperature processed silicon solar cell. VC 2013 AIP Publishing LLC [http://dx.doi.org/10.1063/1.4803446]