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Line 1: − − == Theory of SiPM operation: review questions == − − # What is a semiconductor? How is it differ from a conductor? from an insulator? − # Sketch a diagram of a semiconductor diode and label the parts. What is meant by the ''deletion region''? Where is the depletion region in a diode? − # What is meant by the term ''bias voltage'' in a diode circuit? What does it mean to say that a diode is ''reverse biased''? − # What is diode breakdown and how does it occur? What normally happens when a diode is reverse-biased above the breakdown voltage? − # Describe a way that a reverse-biased diode be connected in a circuit so that it can survive breakdown. What modification to the circuit is required to make the diode produce avalanche pulses? − # What is a ''photodiode''? How does it differ from an ordinary diode? − # What is an ''avalanche photodiode''? How does it differ form an ordinary photodiode? − # What role does temperature play in the performance of an avalanche photodiode? − − − − # A semiconductor is a material that conducts electricity in specific circumstances. Therefore, depending on the conditions under which it is operating, it can act as a conductor or an insulator. Conductors are materials with many free electrons and/or holes that allow electrons to freely pass through it. An insulater has it's electrons firmly bound in it therefore does not allow electrons to pass through it. − # A depleated reigion is a region where there are no holes and no electrons in a semiconductor, therefore making it a insulater at that condition. [[Image:Diode_Diagram.JPG]] − # Bias voltage is the voltage it takes to get the diode to start conducting. Below a certain voltage, the diode will no work even in the forward direcction. It is the voltage which allows the electrons and holes to overcome the depleated zone and meet with each other, creating current. Reverse Biased means that the positive end of the battery is connected with the n-type semiconductor and the negative end is connected with the p-type semicondutor. This sucks all the electrons from the n-type reigion and filled in all the holes in the p-type reigion, creating a large depleated zone. − # Diode breakdown happens when a reverse biased diode is subjected to so much voltage that it conducts in the reverse direction. When a diode is biased past the bias voltage, it stays in a metaphysical state, so by itself, it would stay an insulater, but anything at all (such as a temperature fluctionation) would cause the diode to draw so much current that would cause excessive heat that will destroy a diode. − # If a resister is placed in the circuit, it prevents the amperage to get too high and stops the diode from being fried. If the amps do get too high, then the resister would lower the voltage and the amps by creating resistance and turning the excess energy to heat. To make an avalanche-like pulse, you would also a capacitor that would be connected to the diode. It serves as a tempoary battery that allows the voltage and amperage to get high and create a pulse, then the capacitor will become drained and the resister would lower the voltage to below breakdown and the system would reset itself. − # A Photodiode is a diode that is especially sensitive to light. It is usually made with a clear glass or plastic case that allows light through to maximize the effect light has upon the diode − # An avalanche photodiode is a diode designed in such a way that it releases a pulse of electrons per photon instead of just one. In the process mentioned beforehand, the avalanche photodiode uses the energy from the photon to throw the photodiode off its metastable state and create a pulse. − # Temperatures are caused by vibrations of atoms and a higher temperature would cause more random thermal fluctionsations. Some of these thermal fluctuations have enough energy to throw the photodiode off its metastable state also, causing misfirings.
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The paper will cover the temperature dependence of the SiPM in relation to the dark rate and ability to see peaks. The bias voltage can be kept constant at the nominal value recommended by the manufacturer because I didn't do any testing regarding this aspect of the experiment. The data will be taken from the measurements carried out at UConn during June - July 2007. I will analyze these data and determine the dark rate at each temperature setting, and estimate the uncertainty. These data will be compared to a theoretical model consisting of an electron gas with a single band gap.
The paper will cover the temperature dependence of the SiPM in relation to the dark rate and ability to see peaks. The bias voltage can be kept constant at the nominal value recommended by the manufacturer because I didn't do any testing regarding this aspect of the experiment. The data will be taken from the measurements carried out at UConn during June - July 2007. I will analyze these data and determine the dark rate at each temperature setting, and estimate the uncertainty. These data will be compared to a theoretical model consisting of an electron gas with a single band gap.