Paliwal, A and Singh, K and Mathew, M
(2018)
InAIN/GaN Lattice Matched Stepped-Miniband Superlattices as Efficient Electron Blocking Layer for 450 nm Laser Diode.
In: International Workshop on Nitride Semiconductors (IWN-2018), November 11-16, 2018, Kanazawa, Japan.
Abstract
In this work, we have designed lattice matched, stepped-miniband GaN/In 0.18 Al 0.82N short period superlattices (SPSL) electron blocking layer (EBL) for 450 nm high power laser diode (LD) structure. Due to In 0.18 Al 0.82N alloy is lattice matched with GaN, the strain in the SPSL EBL structure layer is negligible. In the original reference LD structure, EBL was 30 nm Al 0.15 Ga 0.85N layer. The optimized stepped-miniband SPSL structure contains 2 periods of 5 monolayers (ML) GaN/ 1ML In 0.18Alo.82N, 4 periods of 3 ML GaN/1ML In 0.18Al 0.82N, and 15 periods of 1ML GaN/1ML Ino 18Alo.82N. Thickness of SPSL EBL is 29.9 nm. In optimized EBL, the energy barrier height due to miniband increases toward p-cladding in conduction band such that electron leakage is suppressed efficiently. With 1ML thickness of well and barrier, the miniband of SPSL shifts up in conduction band and down in valence band, which results in increase in effective bandgap. The increased effective bandgap blocks electron overflow efficiently. On the other hand, the holes transport occurs through SPSL miniband in valence band, effectively reduced bandgap due to minibands in 5ML well and 3ML well of SPSL enhances the hole injection into the active region. Due to varied well width of SPSL, the structure of EBL results into a stepped miniband SPSL.
With our optimized SPSL EBL design, the threshold current density decreases from 4.9 kA-cm-2 to 4.5 kA-em-2. Light output power of LD was increases from 146.54 mW to 255.26 mW at 10 kA-cm-2 injected current. Slope efficiency increases from 0.548 W/A to 0.924 W/A and leakage current reduces from 2534.6 A-cm-2 to 0.45 A-cm-2 at injected current 10 kA-cm-2.
Actions (login required)
 |
View Item |
Download Statistics
Download Statistics