Abstract: A nitride semiconductor substrate is featured in comprising: a GaN semiconductor layer grown on a base layer, which has a substantially triangular cross-section along the thickness direction thereof, a periodic stripe shapes, and uneven surfaces arranged on the stripes inclined surfaces; and an overgrown layer composed of AlGaN or InAlGaN on the GaN semiconductor layer.

Abstract: A nitride semiconductor substrate is featured in comprising: a GaN semiconductor layer grown on a base layer, which has a substantially triangular cross-section along the thickness direction thereof, a periodic stripe shapes, and uneven surfaces arranged on the stripes inclined surfaces; and an overgrown layer composed of AlGaN or InAlGaN on the GaN semiconductor layer.

Abstract: A nitride semiconductor substrate is featured in comprising: a GaN semiconductor layer grown on a base layer, which has a substantially triangular cross-section along the thickness direction thereof, a periodic stripe shapes, and uneven surfaces arranged on the stripes inclined surfaces; and an overgrown layer composed of AlGaN or InAlGaN on the GaN semiconductor layer.

Abstract: A nitride semiconductor substrate is featured in comprising: a GaN semiconductor layer grown on a base layer, which has a substantially triangular cross-section along the thickness direction thereof, a periodic stripe shapes, and uneven surfaces arranged on the stripes inclined surfaces; and an overgrown layer composed of AlGaN or InAlGaN on the GaN semiconductor layer.

Abstract: The photocathode of the present invention is provided with a supporting substrate composed of a single-crystal compound semiconductor, a light absorbing layer which is formed on the supporting substrate and smaller in an energy band gap than the supporting substrate to absorb incident light transmitted through the supporting substrate, thereby generating photoelectrons, and a surface layer which is formed on the light absorbing layer to lower a work function of the light absorbing layer, in which the supporting substrate comprises Al(1?x)GaxN (0?X<1) and the light absorbing layer comprises a compound semiconductor composed of at least one material selected from the group consisting of Al, Ga and In, and N.

Abstract: A GaN-based semiconductor photocathode is applied to an electron tube. A GaN-based compound semiconductor layer is laterally grown on a substrate, and incorporated in the electron tube. The crystal defects of the compound semiconductor layer are reduced, whereby an electron tube which has inconceivably high sensitivity is realized.

Abstract: A group III nitride semiconductor film involving few lattice defects and having a large thickness, and a process for making the film are disclosed. Dry-etching is conducted while a quartz substrate and a group III nitride semiconductor are placed on the top of a lower electrode. Nano-pillars (50) are formed on the top of the group III nitride semiconductor (101). Another group III nitride semiconductor film (51) is deposited on the nano-pillars (50).