Qbserwation metalorganic of a two-dimensional electron gas in low pressure chemical vapor deposited GaN-AI , Ga , - , N heterojunctions

Abstract

The authors have confirmed the presence of a two-dimensional electron gas (2DEG) in a wide band-gap GaN-Al/sub x/Ga/sub 1-x/N heterojunction by observing steplike features in the quantum Hall effect. The 2DEG mobility for a GaN-Al/sub 0.13/Ga/sub 0.87/N heterojunction was measured to be 834 cm/sup 2//V s at room temperature. It monotonically increased and saturated at a value of 2626 cm/sup 2//V s at 77 K. The 2DEG mobility remained nearly constant for temperatures ranging from 77 to 4.2 K. Using Shubnikov-de Haas (SdH) measurements the two-dimensional carrier concentration was estimated to be 110/sup 11/ cm/sup -2/. The peak mobility for the 2DEG was found to decrease with the heterojunction aluminum compositions in excess of 13%

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