Fabrication and Characterization of Planar-Type Top-Illuminated InP-Based Avalanche Photodetector on Conductive Substrate with Operating Speeds Exceeding 10 Gbps

• Published in: Sensors (Basel, Switzerland) Vol. 18; no. 9; p. 2800
• Main Authors: Liu, Jheng-Jie, Ho, Wen-Jeng, Chiang, Cho-Chun, Teng, Chi-Jen, Yu, Chia-Chun, Li, Yen-Chu
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 25.08.2018; MDPI
• Subjects: Avalanche diodes; avalanche photodetector (APD); charge and multiplication (SAGCM); Chemical vapor deposition; Dark current; Electric fields; Electric potential; Evaluation; eye diagram; grading; modulation frequency; Multiplication; Multiplication & division; multiplication gain; Optical receivers; Organic chemicals; Photometers; Photonics; separate absorption; Taiwan; grading; avalanche photodetector (APD); modulation frequency; multiplication gain; eye diagram; separate absorption; charge and multiplication (SAGCM)
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s18092800

This paper presents a high-speed top-illuminated InP-based avalanche photodetector (APD) fabricated on conductive InP-wafer using planar processes. The proposed device was then evaluated in terms of DC and dynamic performance characteristics. The design is based on a separate absorption, grading, charge, and multiplication (SAGCM) epitaxial-structure. An electric field-profile of the SAGCM layers was derived from the epitaxial structure. The punch-through voltage of the SAGCM APD was controlled to within 16⁻17 V, whereas the breakdown voltage (V ) was controlled to within 28⁻29 V. We obtained dark current of 2.99 nA, capacitance of 0.226 pF, and multiplication gain of 12, when the APD was biased at 0.9 V at room temperature. The frequency-response was characterized by comparing the calculated 3-dB cut-off modulation-frequency (f ) and f values measured under various multiplication gains and modulated incident powers. The time-response of the APD was evaluated by deriving eye-diagrams at 0.9 V using pseudorandom non-return to zero codes with a length of 2 -1 at 10⁻12.5 Gbps. There was a notable absence of intersymbol-interference, and the signals remained error-free at data-rates of up to 12.5 Gbps. The correlation between the rise-time and modulated-bandwidth demonstrate the suitability of the proposed SAGCM-APD chip for applications involving an optical-receiver at data-rates of >10 Gbps.