NOVELTY - The photovoltaic element (10) has a p-type non-crystalline semiconductor film (13) and a first transparent conductive film (14) that are laminated on a side of an n-type crystalline semiconductor substrate (11). An n-type non-crystalline semiconductor film (16) and a second transparent conductive film (17) are laminated on another side of the substrate. The films are formed by crystalline indium oxide that is doped with multiple elements in a group-4, group-5 or group-6 of a periodic table. Average in-surface crystal grain major axis size of the oxide is greater than 10nm and less than 300nm.    USE - Hetero-junction type photovoltaic element i.e. solar cell e.g. crystal silicon based solar cell.    ADVANTAGE - The average in-surface crystal grain major axis size of the crystalline indium oxide is controlled to 300 to 2000 nm to improve photoelectric conversion efficiency. The photovoltaic element ensures that indium tin oxide (ITO) of the transparent conductive films with high carrier mobility and small crystal grain size can be laminated at relatively high temperatures i.e. greater than 200 degree Celsius or subjected to heat treatment so as to reduce series resistance rate by crystallization. The elements include the first set of sub-elements such as group of tungsten and tantalum and the second set of sub-elements such as group of titanium, vanadium and niobium so as to ensure better low-temperature crystallinity and controllability of crystal grain size and improve power generating efficiency and productivity of the photovoltaic element. The n-type crystalline semiconductor substrate achieves n-type semiconductor characteristics without limitations. The photovoltaic element easily reduces carrier recombination rate when film thickness is about less than 1 nm and ensures reduction of short-circuit current or increase in light absorption amount when the film thickness exceeds 10 nm. The photovoltaic element performs sputtering process at low cost with formation temperature of about 200 degree Celsius or less than 200 degree Celsius by controlling the film thickness to form the transparent conductive films.    DETAILED DESCRIPTION - The n-type crystalline semiconductor substrate is a monocrystalline or polycrystalline substrate.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of a photovoltaic element.    Hetero-junction type photovoltaic element (10)    N-type crystalline semiconductor substrate (11)    P-type non-crystalline semiconductor film (13)    Transparent conductive films (14, 17)    N-type non-crystalline semiconductor film (16)