Internal loss of AlGaN-based ultraviolet-B band laser diodes with p-type AlGaN cladding layer using polarization doping
Tomoya Omori, Sayaka Ishizuka, Shunya Tanaka, Shinji Yasue, Kosuke Sato, Yuya Ogino, Shohei Teramura, Kazuki Yamada, Sho Iwayama, Hideto Miyake, Motoaki Iwaya, Tetsuya Takeuchi, Satoshi Kamiyama, Isamu Akasaki
Abstract
Aluminum gallium nitride (AlGaN)-based ultraviolet-B band laser diodes (LDs) with a p-type AlGaN cladding layer using polarization doping were fabricated on lattice-relaxed Al0.6Ga0.4N/AlN/sapphire. The threshold current density Jth and lasing wavelength of this LD were 25 kA cm−2 and 298 nm, respectively. The internal loss (αi) was estimated by means of a variable stripe length method using optical excitation. The αi value of this LD was relatively low (i.e. <10 cm−1), thus suggesting that the device is characterized by both, proper light confinement and low internal loss.