Gallium nitride semiconductor light emitting element

Abstract

Provided is a gallium nitride semiconductor light emitting element wherein a drive voltage is stabilized by reducing spontaneous polarization generated on an interface between an AlGaN semiconductor layer and a GaN semiconductor layer and carrier depletion due to piezo polarization. On a plane (R) of a sapphire substrate (1), a gallium nitride semiconductor crystal (2) including a light emitting region is formed. In other constitution, on a plane (A) or a plane (M) of GaN substrates (3, 4), the gallium nitride semiconductor crystal (2) is formed. Since the growing planes of these gallium nitride semiconductor crystals (2) are nonpolar planes and not an N (nitrogen) polar plane nor a Ga polar plane, an electric field caused by spontaneous polarization and piezo polarization generated on a GaN / AlGaN interface on a p-side can be reduced and carrier depletion can be eliminated.

Description

Technical field [0001] The present invention relates to a gallium nitride semiconductor light emitting element using GaN. Background technique [0002] As semiconductor light emitting elements such as semiconductor laser elements and light emitting diodes that emit blue or violet light, there are gallium nitride semiconductor light emitting elements. When manufacturing GaN-based semiconductor elements, it is difficult to manufacture a substrate made of GaN, so a GaN-based semiconductor layer is epitaxially grown on a substrate made of sapphire, SiC, Si, or the like. [0003] For example, using MOCVD (metal organic vapor growth method), an undoped GaN buffer layer, n-GaN contact layer, n-AlGaN cladding layer, n-GaN optical guide layer, and n-GaN optical guide layer are sequentially formed on the (0001) surface of a sapphire substrate. InGaN multiple quantum well (MQW) active layer, etc., p-GaN optical guide layer, p-AlGaN cladding layer, p-GaN contact layer, etc. are sequentially f...

AI Technical Summary

Problems solved by technology

[0009] But on the p side, as in Figure 10 As shown, since the electric field E is generated from the p-GaN optical guiding layer 44 toward the p-AlGaN cladding layer 45, the holes flowing from the p-AlGaN cladding layer 45 into the p-GaN optical guiding layer 44 are affected by the generated electric field E. Electric repulsion makes it difficult to flow into the MQW active layer 43, resulting in depletion of the carrier and increasing the driving voltage

An increase in driving voltage shortens the lifetime of GaN semiconductor light-emitting devices

[0010] In particular, the p-AlGaN cladding layer 45 contains Mg as a p-type impurity, and when the Mg concentration is 1×10 19 cm -3 Below, the piezoelectric polarization occurring at the interface between the p-GaN optical guiding layer 44 and the p-AlGaN cladding layer 45 sharply increases, Figure 10 The electric field E shown can become unusually large and thus become a problem

Images