Optical identification of silicon as a shallow donor in MOVPE grown homoepitaxial AlN

• Published in: physica status solidi (b) Vol. 249; no. 3; pp. 511 - 515
• Main Authors: Neuschl, Benjamin, Thonke, Klaus, Feneberg, Martin, Mita, Seiji, Xie, Jinqiao, Dalmau, Rafael, Collazo, Ramón, Sitar, Zlatko
• Format: Journal Article
• Language: English
• Published: Berlin WILEY-VCH Verlag 01.03.2012; WILEY‐VCH Verlag
• Subjects: AlN; donor; exciton; homoepitaxy; photoluminescence; silicon
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.201100381

Aluminum nitride (AlN) layers doped intentionally with different concentrations of silicon atoms acting as shallow donors were grown by MOVPE on bulk c‐plane AlN to minimize dislocations in the doped layers; typical values for the dislocation density in the bulk AlN substrates are less than 104 cm−2. The actual silicon concentration was confirmed by secondary ion mass spectroscopy (SIMS) analysis and ranging from 1017 to 1019 cm−3. In highly resolved low temperature photoluminescence (PL) investigations, we found dominating bandgap‐related sharp emission lines with linewidth lower than 500 µeV for undoped samples. We tentatively assign silicon as the shallow donor causing the bound exciton line with 28.5 meV exciton localization energy, for which we found an intensity ratio relative to the free exciton line being linearly dependent on the silicon concentration. For increasing Si content, the respective emission band also broadened asymmetrically and shifted to lower energies as expected from the analogy with other semiconductor systems.