Enhanced Mg Doping Efficiency in P-Type GaN by Indium-Surfactant-Assisted Delta Doping Method

Abstract

An indium-surfactant-assisted delta doping method is reported to enhance the hole concentration and doping efficiency of Mg-doped p-type GaN grown by metal organic chemical vapor deposition. The hole concentration is increased to 1.5×1018 cm-3 by using this method, which is 92% higher than that of conventional delta doping. This higher carrier concentration leads to an improved doping efficiency of 12%. Secondary ion mass spectroscopy reveals that the Mg incorporation is increased by the In surfactant. Photoluminescence analysis suggests that the nitrogen vacancies may be suppressed by the induced indium. Temperature-dependent Hall measurements indicate that the Mg ionization energy and compensation ratio are reduced by the In surfactant.

Analysis on the enhanced hole concentration in p‐type GaN grown by indium‐surfactant‐assisted Mg delta doping

“…Further experiments need to be performed to clarify the origin of the activation energy reduction. Moreover, the lower rate parameter of α τ = 39 659 obtained in the p‐type GaN sample grown with In surfactant indicates a decreased (D 0 , Mg 0 ) transition rate in this case, which can be ascribed to the fewer neutral Mg acceptors in the p‐type GaN, consistent with the analysis from the reduction of UVL band intensity at 30 K. These optical analysis results are in good agreement with those obtained from the temperature‐dependent Hall‐effect analysis , in which the Mg activation energies are 130 meV and 113 meV for the Mg‐δ‐doped samples grown without and with In surfactant, respectively. Moreover, it was also found that the compensation ratio C decreases from 35% to 24% when the In surfactant is employed, suggesting a suppression of V N .…”

“…Previous SIMS results have shown that the incorporation of Mg dopant can be obviously enhanced by the In surfactant . The Mg concentration increased from 8.8 × 10 18 cm −3 to 1.2 × 10 19 cm −3 when using indium‐surfactant‐assisted δ‐doping, which plays a key role in the enhancement of hole concentration.…”

“…The optimized growth condition for δ‐doping was a period of 20 nm of GaN growth followed by a 30‐s purge step and 48‐s Mg doping. Detailed growth parameters and the source‐supply scheme for this doping method have been reported elsewhere . The In/Ga content ratio in the deposited p‐type layer is about 0.017%, as determined by secondary ion mass spectroscopy (SIMS) measurements.…”

“…Using Mg‐δ‐doping, a hole concentration of 9.4 × 10 17 cm −3 has been obtained in MOCVD‐grown p‐GaN, still leaving room for further improvement. Recently, a Mg‐δ‐doping method assisted with indium surfactant has been proposed to improve the carrier concentration in p‐type GaN grown at a low temperature of 920 °C . By using this method, the hole concentration was increased 92% in comparison to that in the conventionally Mg‐δ‐doped sample.…”

High doping efficiency in p-type Al-rich AlGaN by modifying the Mg doping planes

“…The hole concentration was significantly increased, contributing most to the enhanced electrical conductivity with a resistivity comparable to those of the state-of-the-art p-GaN. 27,28 Besides, the hole mobility of the PTGF sample is also slightly higher than that of the control sample, despite the higher hole concentration. This is likely due to the reduced dislocation scattering.…”