Ga2O3 BASED SINGLE CRYSTAL SUBSTRATE AND CRYSTAL LAMINATED STRUCTURE

PROBLEM TO BE SOLVED: To provide a -GaObased single crystal substrate in which variation of donor concentration is suppressed under a reduction atmosphere or an inert gas atmosphere, and a crystal laminated structure capable of epitaxially growing a high quality crystal film having small variation in quality under the reduction atmosphere or the inert gas atmosphere.SOLUTION: The -GaObased single crystal substrate has a donor concentration corresponding to an added concentration of Si, Hf, Ge,Sn, Ti or Zr as an IV group element or an added concentration of two or more kinds of the IV group elements, the donor concentration increasing along a linear straight line having a predetermined inclination according to increase of the concentration of the IV group element in logarithm rectangular coordinates using the concentration of the IV group element as a horizontal axis and using the donor concentration as a vertical axis. The crystal laminated structure includes a GaN based epitaxial crystal film formed on the -GaObased single crystal substrate. 【課題】還元雰囲気や不活性ガス雰囲気下におけるドナー濃度の変化が抑えられたβ−Ｇａ２Ｏ３系単結晶基板、及び還元雰囲気や不活性ガス雰囲気下において品質のばらつきの小さい高品質な結晶膜をエピタキシャル成長させることのできる結晶積層構造体を提供する。【解決手段】ＩＶ族元素としてのＳｉ、Ｈｆ、Ｇｅ、Ｓｎ、Ｔｉ、あるいはＺｒが添加された濃度、あるいは２種以上の前記ＩＶ族元素が添加された濃度に応じたドナー濃度を有するβ−Ｇａ２Ｏ３系単結晶基板であって、前記ＩＶ族元素の濃度を横軸に取り、前記ドナー濃度を縦軸に取った対数直交座標において、前記ドナー濃度が、前記ＩＶ族元素の濃度の増加に応じて所定の傾斜を有した正比例直線に沿って増加されたβ−Ｇａ２Ｏ３系単結晶基板、及び前記β−Ｇａ２Ｏ３系単結晶基板上に形成されたＧａＮ系エピタキシャル結晶膜を含む結晶積層構造体を提供する。【選択図】図１