Fabrication of high-speed resonant cavity enhanced Schottky photodiodes

Abstract

Abstract-We report the fabrication and testing of a GaAsbased high-speed resonant cavity enhanced (RCE) Schottky photodiode. The top-illuminated RCE detector is constructed by integrating a Schottky contact, a thin absorption region (In 0:08 Ga 0:92 As) and a distributed AlAs-GaAs Bragg mirror. The Schottky contact metal serves as a high-reflectivity top mirror in the RCE detector structure. The devices were fabricated by using a microwave-compatible fabrication process. The resulting spectral photo response had a resonance around 895 nm, in good agreement with our simulations. The full-widthat-half-maximum (FWHM) was 15 nm, and the enhancement factor was in excess of 6. The photodiode had an experimental setup limited temporal response of 18 ps FWHM, corresponding to a 3-dB bandwidth of 20 GHz.

Design of Ultra Fast RCE Photodetectors for Optical Communications systems

“…The theoretical result is also in very good agreement with recently published experimental data on high-speed RCE Schottky photodiodes (Jervase, 2000), , and high-speed Si-based RCE photodetectors (Ozbay, 1997). With reference to Figure 2, the use of the free spectral range (FSR) to the wavelength full width at half maximum (FWHM) as a measure of wavelength selectivity of detection (Kishino, 1991) is no longer valid.…”

“…One of the promising types is the Resonant Cavity Enhanced (RCE) photodetector. In the RCE, the active region is placed inside a Fabry-Perot cavity between two mirrors made of quarter-wave stacks (QWS) to allow the signal light to have more than one absorbing path inside the active region (Kishino, 1991), (Unlu, 1992(Unlu, , 1995, (Tan, 1995), , (Tung, 1997), (Jervase, 1998(Jervase, , 2000, , (Ozbay, 1997). The resulting structure will need only a very thin absorbing intrinsic region to achieve high quantum efficiency as well as a high speed of response.…”

Design and optimization of high-speed resonant cavity enhanced Schottky photodiodes

“…Furthermore, RCE pin PD's usually employ distributed Bragg reflectors (DBR's) as a high-reflectivity top mirror. In contrast, when a top-illuminated RCE scheme is employed, a thin semitransparent Schottky contact [1], [6] readily eliminates the lateral access resistance problem, allows for a shorter cavity, and increases the air-semiconductor interface reflectivity [7] without the need for a top DBR. The cavity resonance can be tuned to the desired wavelength by recessing the top surface prior to fabrication [8], [9], which is a significant advantage of these devices.…”

“…The cavity resonance can be tuned to the desired wavelength by recessing the top surface prior to fabrication [8], [9], which is a significant advantage of these devices. While the bandwidth-efficiency improvement of RCE detection has been fully exploited for pin [10] and avalanche PD's [11], there have been only a few reports on RCE Schottky PD's [7], [12], [13]. The first RCE Schottky PD was reported by Chin et al [12].…”

45 GHz bandwidth-efficiency resonant cavity enhanced ITO-Schottky Photodiodes

“…Theoretical simulations predict even better performances for RCE Schottky PDs if one can get rid of the optical losses and scattering caused by the Schottky metal, Au, which also serves as the top mirror of the RC [7], [11]. Indium-tin-oxide (ITO), which is known to be a transparent conductor, is a potential alternative to thin semitransparent Au as the Schottky-contact material.…”