Implantation induced electrical isolation of sulphur doped GaNxAs1−x layers

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Vol. 237; no. 1-2; pp. 102 - 106
• Main Authors: Ahmed, S., Lin, J., Haq, A., Sealy, B.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-08-2005
• Subjects: 72.80.Er; 81.05.Ea; 81.15.Hi; Cold implants; Electrical isolation; GaNAs; III-N-V; Ion implantation; III-N-V; 72.80.Er; Ion implantation; GaNAs; Cold implants; Electrical isolation; 81.15.Hi; 81.05.Ea
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/j.nimb.2005.04.110

The study of III-N-V semiconductor alloys, especially GaNxAs1−x has been increasing in the last few years. The strong dependence of the band gap on the nitrogen content has made this material important for a variety of applications, including long wavelength optoelectronic devices and high efficiency solar cells. We report on the effects of sulphur doping implants on the achieved electrical isolation in GaNxAs1−x layers using proton bombardment. Sulphur ions were implanted in MOCVD-grown GaNxAs1−x layers (1.4μm thick with nominal x=1%) with multiple energies creating approximately uniform doping profiles in the range of about 1×1018–5×1019cm−3. Several proton implants were performed in order to find the threshold dose (minimum dose to achieve maximum sheet resistivity) for the electrical isolation of n-type GaNxAs1−x layers. Results show that the sheet resistance of n-type layers can be increased by about five orders of magnitude by proton implantation and the threshold dose to convert a conductive layer to a highly resistive one depends on the original free carrier concentration. The study of annealing temperature dependence of sheet resistivity in proton-isolated GaNxAs1−x layers shows that the electrical isolation can be preserved up to 450 and 500°C when the implantation is performed at RT and 77K with threshold dose, respectively. These results for n-type GaNxAs1−x layers are novel and have ramifications for device engineers.