[TuD1] Advanced Semiconductor Lasers (II)

9:45 AM - 10:00 AM JST(12:45 AM - 1:00 AM UTC)

[TuD1-04] Deep-Ultraviolet AlGaN Laser Diodes Employing Low-Resistivity n-type Ohmic Contacts

〇Kazuaki Ebata¹, Masanobu Hiroki¹, Seiya Kawasaki¹, Kouta Tateno¹, Kazuyuki Hirama¹, Yoshitaka Taniyasu¹ (1. NTT Basic Research Labs. (Japan))

Deep-ultraviolet (deep-UV) AlGaN laser diodes (LDs) emitting below 300 nm are promising for applications such as virus inactivation, environmental sensing, and spectroscopy. However, in high-Al-content AlGaN (Al > 80%), achieving low-resistivity n-type ohmic contacts remains a major challenge. In this study, deep-UV AlGaN LDs were fabricated using a selectively regrown Si-doped compositionally graded AlGaN layer as an n-type contact layer. Circular transmission line method measurements confirmed that this contact layer enables low-resistivity ohmic contact formation even for high-Al-content AlGaN. As a result, the operating voltage of the LDs was significantly reduced, leading to enhanced electron injection efficiency. Under pulsed operation at room temperature, laser oscillation at 284.1 nm was achieved with a threshold current density of 13.5 kA/cm². Polarization-resolved measurements showed that the emission above threshold was dominated by the TE-polarized component, confirming laser oscillation. These results demonstrate that the proposed n-type contact layer is effective for improving the performance of deep-UV AlGaN LDs.