GAN group crystal base member having low dislocation density, use thereof and manufacturing methods thereof

A GaN group crystal base member comprising a base substrate, a mask layer for controlling an extension of dislocation line partially covering the surface of said base substrate to give a masked region, and a GaN group crystal layer grown thereon to cover said mask layer, which is partially in direct contact with a non-masked region of the base substrate, wherein the GaN group crystal layer is a first GaN group crystal layer, which further comprises a second mask layer partially covering the surface of said first GaN group crystal layer and a second GaN group crystal layer grown thereon to cover the second mask layer, which is partially in direct contact with a non-masked region of the first GaN group crystal layer.

A GaN group crystal base member to be used as a crystal substrate of a GaN semiconductor element, comprising a base substrate, a mask layer for controlling an extension of dislocation line partially covering the surface of said base substrate to give a masked region, and a GaN group crystal layer grown thereon to cover said mask layer, which is partially in direct contact with a non-masked region of the base substrate, wherein the base substrate permits growth of a GaN group crystal in the C axis orientation as the thickness direction, and the mask layer is made from a material substantially free from GaN group crystal growth, and wherein the GaN crystal layer has grown to cover the mask layer from a non-masked region as the growth starting point, and the mask layer forms a pattern wherein the width of the part having a low dislocation density within said crystal exceeds the width of an active part of said GaN group semiconductor element.

A GaN group crystal base member to be used as a crystal substrate of a GaN semiconductor element, comprising a base substrate, a mask layer for controlling an extension of dislocation line partially covering the surface of said base substrate to give a masked region, and a GaN group crystal layer grown thereon to cover said mask layer, which is partially in direct contact with a non-masked region of the base substrate, wherein the base substrate permits growth of a GaN group crystal in the C axis orientation as the thickness direction, and the mask layer is made from a material substantially free from GaN group crystal growth, and wherein a masked region having, as outer shape lines, two parallel straight lines extending in the <1-100> orientation of the GaN group crystal to be grown on said base substrate, and the width between the two straight lines being not more than the width of said GaN group semiconductor element and not less than the width of an active part of said element.