Midgap states in metalorganic vapor phase epitaxy grown Al xGa1-xAs

Tamotsu Hashizume, Hideki Hasegawa, Hideo Ohno

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13 Citations (Scopus)


The electrical properties of midgap states in n-type AlxGa 1-xAs grown by the metalorganic vapor phase epitaxy were investigated by the deep level transient spectroscopy and photocapacitance (PHCAP) techniques. A new PHCAP measurement procedure to avoid interference from the photoionization of the DX center was used. Two near-midgap levels, i.e., a higher lying MH level and a lower lying ML level were detected. As AlAs mole fraction, x, is increased, the energy positions of these two levels became deeper, maintaining a remarkable horizontal alignment with respect to the hybrid orbital energy level. The ML level showed a clear photoquenching for x<0.3, but the quenching disappeared for x≳0.3. No photoquenching of the MH level was observed for all x investigated. Similarity of the photoquenching behavior to GaAs1-x Px as well as its energy position and optical cross sections led to the conclusion that the ML level is an As-related EL2-like defect. On the other hand, the MH level originates from a defect related to Al.

Original languageEnglish
Pages (from-to)3394-3400
Number of pages7
JournalJournal of Applied Physics
Issue number7
Publication statusPublished - 1990


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