The polarization field in Al-rich AlGaN multiple quantum wells

• Published in: Japanese Journal of Applied Physics Vol. 58; no. SC; p. SCCC10
• Main Authors: Guo, Qiang, Kirste, Ronny, Mita, Seiji, Tweedie, James, Reddy, Pramod, Washiyama, Shun, Breckenridge, M. Hayden, Collazo, Ramón, Sitar, Zlatko
• Format: Journal Article
• Language: English
• Published: Tokyo IOP Publishing 01.06.2019; Japanese Journal of Applied Physics
• Subjects: Aluminum gallium nitrides; Aluminum nitride; Carrier density; Cladding; Electric field strength; Electric fields; Piezoelectricity; Polarization; Quantum wells; Single crystals; Stark effect; Substrates
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/1347-4065/ab07a9

This paper investigates the quantum confined Stark effect in AlGaN multiple quantum well structures with a high Al content grown on single-crystalline AlN substrates. The quantitative relationship between the quantum well structure parameters, photogenerated carrier density, built-in electric field and ground-level emission is discussed. It is found that the electric field strength increases from 0.5 MV cm−1 to almost 3 MV cm−1 when the Al content in the quantum well barriers is increased from 65% to 100%, which is consistent with the theory of spontaneous and piezoelectric polarization in III-nitrides. In addition, the built-in electric field increases significantly with increasing barrier thickness. Based on these results, the electric field in an Al0.55Ga0.45N single quantum well with AlN cladding is predicted to be around 5 MV cm−1.