Hydrodynamic Simulations of Unitraveling-Carrier Photodiodes

• Published in: IEEE journal of quantum electronics Vol. 43; no. 11; pp. 1088 - 1094
• Main Authors: Rahman, S.M.M., Hjelmgren, H., Vukusic, J., Stake, J., Andrekson, P.A., Zirath, H.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.11.2007; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Absorption; Applied sciences; Bandwidth; Computational fluid dynamics; Computer simulation; Doping; Electron optics; Electronics; Exact sciences and technology; Fluid flow; Hot carriers; Hydrodynamics; Indium gallium arsenide; Modulation; Optical modulation; Optoelectronic devices; Photodiodes; photodiodes (PDs); Road transportation; semiconductor device modeling; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; semiconductor heterojunctions; Semiconductor process modeling; Space charge; Ternary compound; Optical injection; Gallium arsenides; Space charge; Hot carriers; Photodiode; Experimental study; Doping profile; Indium arsenides; photodiodes (PDs); Response function; Semiconductor device; semiconductor device modeling; Semiconductor heterojunctions; Hydrodynamic model; Hot carrier
• ISSN: 0018-9197; 1558-1713; 1558-1713
• DOI: 10.1109/JQE.2007.905885

We present simulated results of a unitraveling-carrier photodiode (UTC-PD) using the hydrodynamic carrier transportation model. A maximum responsivity of 0.25 A/W and a small-signal 3-dB bandwidth of 52 GHz were obtained for a 220-nm-thick InGaAs absorption layer. The physical properties of the UTC-PD have been investigated at different optical injection levels. Modulation of the energy-band profile due to the space charge effect has been observed at high injection level, and an electron velocity overshoot of 3 x 10 7 cm/s has been found to effectively delay the onset of space charge effects. Comparisons with reported simulated results using the drift-diffusion model as well as reported experimental results are presented. The results suggest the necessity of using the hydrodynamic transport equations to accurately model the UTC-PD. In addition, it has been corroborated that the photoresponse of the UTC-PD could be improved by incorporating a graded doping profile in the absorption layer.