Abstract: The invention provides a method for producing a group III nitride based semiconductor having a reduced number of crystal defects. A GaN layer 2 is epitaxially grown on a sapphire substrate 1 having C-plane as a main plane (FIG. 1A). Then, the layer is wet-etched by use of a 25% aqueous TMAH solution at 85° C. for one hour, to thereby form an etch pit 4 (FIG. 1B). Then, a GaN layer 5 is grown on the GaN layer 2 through the ELO method (FIG. 1C). The thus-formed GaN layer 5 has a screw dislocation density lower than that of the GaN layer 2.

Abstract: A HEMT has a drain region adapted to be electrically connected to a high voltage of an electric source, a source region adapted to be electrically connected to a low voltage of the electric source. A first semiconductor region is disposed between the drain region and the source region. A MIS structure and a heterostructure are disposed at a surface of the first semiconductor region. The MIS structure includes a gate electrode that faces a portion of a surface of the first semiconductor region with a gate insulating membrane therebetween. The heterostructure includes a second semiconductor region which makes contact with a rest portion of the surface of the first semiconductor region and has a wider band-gap than the first semiconductor region. The drain region and the source region are capable of being electrically connected with a structure in which the MIS structure 40 and the heterostructure are arranged in series.

Abstract: A group III nitride based semiconductor device which has a trench or mesa structure and of which leakage of current and reduction of breakdown voltage are prevented. A GaN layer 2 was grown on a C-plane sapphire substrate 1, and a T-shaped USG film 3 was formed on the GaN layer 2 so that side surfaces of the USG film 3 were arranged parallel to A-plane and M-plane of the GaN layer 2. Thereafter, by using the USG film 3 as a mask, the GaN layer 2 was dry-etched. As is clear from FIGS. 2A and 2B, the M-plane is less roughened as compared with the A-plane. Subsequently, wet-etched was performed by use of an aqueous TMAH solution. As is clear from FIGS. 2C and 2D, roughness of the A-plane and the M-plane are removed, and, particularly, the M-plane assumes a mirror surface. Thus, through provision of M-plane side surfaces of a trench or an etching-formed mesa, leakage of current and reduction of breakdown voltage of a group III nitride based semiconductor device can be prevented.

Abstract: The present invention relates to a modified physiologically active protein, modified physiologically active proteins produced by the process and pharmaceutical compositions containing the same.

Abstract: The present invention relates to a polyethylene glycol-bound ligand in which polyethylene glycol is bound to a ligand having a binding affinity for a specific receptor or a specific protein (i.e.