Transport equations and Ramo's theorem: Applications to the impulse response of a semiconductor detector and to the generation-recombination noise in a semiconductor junction

Exact analytical expressions are derived for the short circuit photodiode currents excited by light pulses, under the assumption that the drift carrier velocity linearly depends on the electric field in the depletion layer. Reflection from the back surface of the photodiode is taken into account. Using the obtained expressions it is possible to establish a connection between the rise time t rise and the product αW eff of the absorption coefficient α(λ) and effective depletion layer width W eff ( W ) at various ratios of the diode thickness and the effective depletion layer width. The influence of the RC -constant (where C is the photodiode effective capacity and R is the sum of the diode series and loading resistances) on the rise time is also analyzed. One of the most important conclusions is that generally the rise time is larger for p - n - n + photodiode configurations than for n - p - p + configurations at the same substrate resistivity.

Rise time of silicon p-n-p photodiodes

Metallurgical reactions in Au/(InGe) ohmic contacts to GaAs

Publisher Summary This chapter concentrates on photodetectors for optical communications, and the choice of the detector and the detection scheme is determined by system requirements. The detector diodes have to be designed very carefully in order to exploit the large information capacity and take advantage of the potentially long-haul transmission with large repeater distances offered by optical transmission. This chapter intends to summarize the design criteria for such devices and supply the system designer with the information he needs to choose the optimum diode for a particular system demand. The chapter presents the physical effects underlying the function of a photodiode, and theoretical and physical limits for their performance is given. The equations characterizing a particular diode is derived and the principles for the design of optical receivers are summarized. The chapter overviews detector diodes made from different semiconductor materials and their corresponding device structure for the present state of the art. The chapter presents optical detectors for integrated optics and special applications. The chapter summarizes and gives a short outlook on the future developments in the field of detectors for optical communication.

Photodiodes for Optical Communication

The Au/(In–Ge) contact to GaAs was investigated to discover the metallurgical structure of the contact–GaAs interface. A variety of intermetallic phases in the form of precipitate particles or thin films were identified, and their presence was correlated with the temperature at which the contacts were fired. The possibility of predicting the structures of the fired contacts from simple metallurgical phase diagrams is discussed, and some evidence on the influence of the precipitating phases on the electrical character of the contacts is reviewed.

Metallurgical Reactions in Au/(In–Ge) Ohmic Contacts to GaAs

An exact simulation of a Silicon PIN photodetector with transient light excitation is presented. The photodetector under consideration is designed to have good responsivity and fast response time in the wavelength range 0.6–0.95 μm which is of interest in fiber optic communication systems driven by GaAs and AlGaAs light sources. The photocurrent transient is computed for step and impulse light excitation using various values of reverse voltage, intrinsic layer thickness and doping. Good agreement is obtained between calculated and experimental waveforms.

M. De Padova

Papers

PIN photodetector under transient conditions: Simulation and experiments