AlGaN-Based Lateral Current Injection Laser Diodes Using Regrown Ohmic Contacts

Abstract

A lateral current injection (LCI) design for AlGaN deep-ultraviolet edge-emitting laser diodes (LDs) on AlN substrates is presented. Two-dimensional optoelectronic simulation predicts lasing at a wavelength of 290 nm. Unlike vertical current injection designs, LCI designs can take advantage of narrow-bandgap p-type contact layers with minimal impact on the optical confinement factor through a partial decoupling of the problems of optical confinement and electrical injection. With polarization-charge-matched quantum well barriers, a large number of quantum wells can be used in LCI designs, which not only enhances the optical confinement factor but also distributes joule heating over a large volume. This is the first theoretical investigation of an LCI LD design in the III-V nitride material system.Index Terms-AlGaN active layer, AlN substrate, deep ultraviolet laser diodes, lateral current injection, polarization charge, quaternary barrier, regrown ohmic contacts.

Advanced Middle-UV Coherent Optical Sources

“…To circumvent all issues surrounding vertical injection designs in the DUV emission range, we have proposed a lateral current injection (LCI) LD design exploiting polarization-matched quaternary QWBs and regrown Ohmic contacts [15]. We have further demonstrated that such LCI LD designs significantly decouple the problem of electrical injection from that of optical confinement.…”

“…Our numerical simulations have demonstrated that regrown Ohmic result in no artificial blocking layers for lateral charge injection, but additionally serve to inhibit leakage of carriers from the active region and loss of quantum efficiency. Although the LCI LD design has already been proposed in the literature to be used as longer wavelength active sources in optoelectronic integrated circuits using GaInAsP/InP and related material systems, we presented the first theoretical demonstration [15] that this approach is also feasible for UV LDs operating at sub-300 nm wavelengths in the III-V nitride material system. Table 3 shows the epitaxial structure of a 290 nm edge-emitting LCI LD design using polarization-charge-matched quaternary QWBs and regrown Ohmic contacts.…”