Effects of the intrinsic layer width on the band-to-band tunneling current in p-i-n GaN-based avalanche photodiodes

• Published in: Semiconductor science and technology 2009-09, Vol.24 (9), p.095006-095006 (5)
• Main Authors: Wang, Ling, Bao, Xichang, Zhang, Wenjing, Li, Chao, Yuan, Yonggang, Xu, Jintong, Zhang, Yan, Li, Xiangyang
• Format: Article
• Language: English
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Optoelectronic devices; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
• ISSN: 0268-1242; 1361-6641
• DOI: 10.1088/0268-1242/24/9/095006

Dark current is critical for GaN-based avalanche photodiodes because it significantly increases the noise current and limits the multiplication factor. It has been found that the band-to-band tunneling current is the dominant origin of the dark current for avalanche photodiodes at the onset of breakdown voltage. Experimentally, for GaN-based avalanche photodiodes with a thinner intrinsic layer, the dark current increases nearly exponentially with the applied voltage even at a lower bias voltage. In this paper, the intrinsic layer (i-layer) width of GaN-based avalanche photodiodes has been varied to study its effect on the band-to-band tunneling current. A widely used equation was used to calculate the band-to-band tunneling current of avalanche photodiodes with different i-layer widths (i-layer 0.1 mum, 0.2 mum and 0.4 mum). At -40 V, the band-to-band tunneling current significantly reduces by a magnitude of 10-15 A with an increase in the i-layer width from 0.1 mum to 0.2 mum, and a magnitude of 10-29 A with an increase in the i-layer width from 0.2 mum to 0.4 mum. Then, GaN-based avalanche photodiodes (i-layer 0.1 mum, 0.2 mum and 0.4 mum) with different-sized mesa were fabricated. Also, the measurement of dark current of all three different structures was performed, and their multiplication factors were given.