Investigation of Mg δ-doping for low resistance N-polar p-GaN films grown at reduced temperatures by MOCVD. (9th August 2018)

• Record Type: Journal Article
• Authors: Lund, Cory; Agarwal, Anchal; Romanczyk, Brian; Mates, Thomas; Nakamura, Shuji; DenBaars, Steven P; Mishra, Umesh K; Keller, Stacia
• Is Part Of: Semiconductor science and technology. Volume 33:Number 9(2018:Sep.)
• Publication Date: 2018-08-09
• Subjects: p-GaN -- N-polar -- delta-doping -- III-nitrides -- MOCVD; Semiconductors -- Periodicals; 621.38152
• DOI: 10.1088/1361-6641/aad5cf
• Languages: English
• ISSNs: 0268-1242

Abstract

Abstract: In this study we explored p-type δ -doping for the deposition of N-polar p-GaN films at 900 °C, for application in device structures containing high In composition active layers. Various δ -doping process parameters were investigated, including the duration and molar flow of the Mg precursor during each pulse as well as the δ -doping period. The results were compared to those obtained for layers grown using continuous doping. As the δ -doping period was reduced from 25 to 5 nm, the p-GaN bulk resistivity decreased from 6.8 to 2.8 Ω cm. The p-layer resistivity rose with increasing [Mg] independent of the doping scheme. For similar average [Mg], however, continuous doping resulted in a lower resistivity compared to δ -doping. This effect was more pronounced at higher [Mg], indicating that high local concentrations of Mg resulted in degradation of the electrical performance. After optimization of the p-layer structure and contact fabrication process, a minimum contact resistance of 2.77 m Ω cm 2 and a minimum resistivity of 1.33 Ω cm were achieved.