Then, the main structures reported in the literature and the most significant results obtained in recent years are reviewed and discussed, comparing the performance of devices protein inhibitors based on different approaches.2.?Photodetector Performance RequirementsIt is useful to briefly recall the main performance requirements of integrated photodetectors Inhibitors,Modulators,Libraries for NIR optical applications. High speed, high responsivity, low dark current, low bias voltage and small dimensions are appealing properties for a photodetector and research efforts are now aimed at achieving all these in single devices.As bandwidth demand keeps increasing, it is essential that all-silicon photodetectors operate at 5 GHz, a frequency at which hybrid detectors have already been demonstrated [15].
Of course, higher bandwidths (20 GHz, >50 GHz) are desirable in order to anticipate future trends in optical interconnects. In fact, very high-speed photodetectors, combined with dense wavelength division multiplexing (DWDM) technology in the C band (1,528�C1,561 nm) Inhibitors,Modulators,Libraries and L band (1,561�C1,620 nm) [16], have the potential to achieve a bandwidth greater than 0.5 THz.Another important property of a detector is described by its responsivity, which indicates the current produced by a certain optical power. Reasonable responsivities are necessary for an acceptable signal-to-noise ratio and to ease the design and realization of the amplifier circuitry that follows. Responsivity is strictly linked to a device��s quantum efficiency, a property describing how many carriers per photon are collected.
It is worth noting that there is a difference between internal and external quantum efficiency: in the case of internal quantum efficiency, Inhibitors,Modulators,Libraries the number of carriers that contribute to the photocurrent is related to the number of absorbed photons, while in the case of external quantum efficiency, they are related to the number of incident photons. In the telecommunications field a responsivity �� 0.1 A/W [17], corresponding to external quantum efficiencies �� of 15%, 10%, and 8% at �� = 850, 1,300, and 1,550 nm, respectively, is required.In order to evaluate detector performance, an important property is dark current. This is a serious issue because the shot noise, associated with the fluctuations in a measured signal due to the random arrival time of the particles carrying energy, generates a leakage current which can increase the bit error rate (BER).
Dark current depends on work frequency and Inhibitors,Modulators,Libraries it is worth noting that a higher dark current could be allowed if a system worked at frequencies at which Carfilzomib the amplifier noise overcame photodetector noise. In a typical photodetector, dark currents less than 1 ��A are required.A especially further requirement of photodetectors is low-voltage operation. It would be desirable to realize devices operating at the same power supply as the CMOS circuitry, i.e., bias voltage < 5 V and as low as 1 V for advanced CMOS generation.