Study on carrier transport in InGaN upper waveguide layer of GaN-based blue laser diodes

Abstract

The carrier transport capacity of the unintentionally doped InGaN upper waveguide (UWG) layer affects the hole injection efficiency of GaN-based blue laser diode. In this article, we studied the carrier transport property of UWG layer grown under various conditions by metal organic CVD. Hole diffusion length in these samples were obtained by photoluminescence. It is found that higher diffusion length can be obtained with growth temperature around 840 °C–870 °C and V/III ratio about 16 000. It is also found that reducing the threading dislocation density can enhance the carrier transport capacity of the UWG layer. Finally, blue laser diodes (LDs) were fabricated to confirm that increasing the effective diffusion length of carriers in UWG layers can help improve LDs performance.