Effect of dislocations on the growth of p-type GaN and on the characteristics of p-n diodes

Abstract

We investigate the influence of crystal defects on p‐type GaN grown by metalorganic vapor phase epitaxy. Sets of p‐type GaN films were grown on sapphire substrates and on free‐standing GaN (F‐GaN) substrates simultaneously using various Et‐Cp2Mg flow rates. Although there is a difference of two orders of magnitude between the threading dislocation densities of p‐type GaN grown on sapphire and F‐GaN substrates, there is no significant difference in hole concentration. However, there are problems with the surface morphology of p‐type GaN grown on sapphire. The deterioration of the surface was caused by the difference in nanopipe density. The electrical properties of a p–n junction diode formed on sapphire with a high density of nanopipes were observed using emission microscopy under both forward‐ and reverse‐bias conditions. Our results demonstrate that the nanopipes are electrically inactive, and that other types of threading dislocation have more influence on the current–voltage characteristics.

Trap‐Related Breakdown and Filamentary Conduction in Carbon Doped GaN

“…Since GaN is a material with a large concentration of extended defects such as dislocations (≈10 9 cm −2 ) in the next we shortly discuss their possible role. EL spots due to localized conduction have been observed in reverse biased InGaN/GaN light emitting diodes (LEDs) . It has been found that the EL spots occur at the position of screw and mixed dislocations, so it is assumed that the current flows in the leakage paths related to dislocations .…”

“…EL spots due to localized conduction have been observed in reverse biased InGaN/GaN light emitting diodes (LEDs) . It has been found that the EL spots occur at the position of screw and mixed dislocations, so it is assumed that the current flows in the leakage paths related to dislocations . Our results indicate that multiple CFs in the studied GaN:C/n‐GaN structures are formed spontaneously.…”

Dislocations at coalescence boundaries in heteroepitaxial GaN/sapphire studied after the epitaxial layer has completely coalesced

“…As shown in Figure 4, late coalescing boundaries can result in both dislocation clusters and voids. Usami et al 31 have shown examples of atypical dislocations with open cores in GaN/sapphire p-n diodes both severely disrupting the growth morphology and also leading to leakage pathways through the device. Hence, optimization of the growth conditions in the final stages of coalescence, may be important to avoiding "killer defects" in electronic devices for example.…”

Dopant-defect interactions in Mg-doped GaN via atom probe tomography

“…24,27 Many of our understandings on self-compensation mechanisms in GaN:Mg are based on computational models. 13,[28][29][30][31] Experimental verification is often based on measurements taken at the sample scale, such as bulk or averaged concentration, 24,32 dislocation density, 33,34 or hole mobility. 1 There are also limitations in standard experimental techniques, such as the limited lateral resolution of SIMS and lack of depth sensitivity in TEM.…”