Carla Novo

Illuminated to dark ratio improvement in lateral SOI PIN photodiodes at high temperatures

This work presents a study of the illuminated to dark ratio (IDR) of lateral SOI PIN photodiodes. Measurements performed on fabricated devices show a fivefold improvement of the IDR when the devices are biased in accumulation mode and under high temperatures of operation, independently of the anode voltage. The obtained results show that the doping concentration of the intrinsic region has influence on the sensitivity of the diodes: the larger the doping concentration, the smaller the IDR. Furthermore, the photocurrent and dark current present lower values as the silicon film thickness is decreased, resulting in a further increase in the illuminated to dark ratio.

Optimized design of lateral PIN photodiodes regarding responsivity and SNR as a function of operating temperature

This paper addresses a simultaneous analysis of the intrinsic length (L1) and the operating temperature, which are, respectively, a preeminent design variable and a fundamental boundary condition for lateral PIN photodiodes. The analysis is focused in the responsivity and signal-to-noise ratio (SNR), in order to investigate the best configuration for a given technology. CMOS PIN photodiodes with different characteristics were designed and fabricated Experimental measurements were performed and the optical devices showed reasonable performance in the visible spectrum. The best responsivity (37%) was achieved for L1 = 11 μm, at room temperature and light wavelength of 650 nm. The best signal-to-noise ratio was found to be 6000 for red and 700 for blue lights, both at T = 200 K.

Gated SiGe PIN diodes exposed to visible light spectrum and heavy-ion radiation

This paper studies gated PIN diodes designed at Centro Universitário da FEI and fabricated at Global Foundries in the GF0.13 technology, using SiGe substrate and four gate setups. The analysis is made through experimental measurements and numerical simulations of PIN diodes in dark condition, illuminated with visible light or exposed to heavy-ion radiation. Particle beam radiation present in hazard environments may cause circuit malfunctions due to interference in the device response. This paper conducts a brief, but depth study of how these variables impact the PIN diode performance, important to space and sensor applications.

Evaluation of the transit time and frequency response of multifinger PIN SOI photodiodes at IR and UV wavelenghts

This paper addresses a simultaneous analysis of the intrinsic length (LI) variation and substrate doping concentration on the AC operation of multifinger SOI PIN photodiodes, in order to investigate the best performance for each application. The results showed that the best frequency response was achieved for devices with smaller L1 values and higher substrate doping concentrations, reaching a 3 dB frequency of 10 GHz with 400nm of wavelength. However this configuration causes an efficiency reduction, decreasing the photogenerated current and consequently the responsitivy of the device, due to the smaller photosensitive area. The performance of the diodes was analyzed in the UV and IR range. In the first case, SOI photodiodes demonstrated excellent responsivity and high speed operation because the influence of the capacitive effect of BOX can be neglected, since most of the light radiation is absorbed before reaching the substrate, which proves the excellent SOI device performance for applications that requires higher current levels (greater responsivity) in the UV range. However, in applications for short distance optical communication, which require the use of wavelengths in the IR range, the SOI device has demonstrated low responsivity, but also presents excellent speed of response.