Semiconductor Detectors and Their Applications

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Questions and Answers

Match the semiconductor detectors with their primary application:

Silicon Diode Detectors = Gamma spectroscopy Germanium Gamma-ray Detectors = Energy measurement of charged particles Lithium Drifted Silicon Detectors = Tracking and vertexing Scintillation Counters = Tracking, particle identification

Match the semiconductor property with its description:

Valence Band = Electrons bound to specific lattice sites Conduction Band = Electrons free to move through the crystal Bandgap = Determines the type of semiconductor material Electron-Hole Pairs = Information carriers in semiconductor detectors

Match the characteristics of semiconductor diode detectors with their features:

Superior Energy Resolution = Best energy resolution in routine use Compact Size = Small detector dimensions Fast Timing Characteristics = Relatively quick response Radiation-Induced Damage = High susceptibility in small sizes

Match the materials with their impurity levels:

Ge = Several cm Si = Several mm with higher impurity level than Ge Si (high purity) = Lower impurity than Si (higher level) Ge (high purity) = Low impurity compared to Ge Signup and view all the answers

Match the type of detection to its description:

Solid-state Detectors = Use electron-hole pairs as information carriers Gas Detectors = Detection medium with lower density than solids Scintillation Detectors = Based on photoelectric effect with statistical fluctuations Semiconductor Detectors = Yield larger number of charge carriers Signup and view all the answers

Match the solid-state detector applications with their fields:

Nuclear Physics = Gamma spectroscopy and energy measurement Particle Physics = Tracking and beam condition monitoring Satellite Experiments = Particle identification and tracking Security and Medicine = Applications in health and safety monitoring Signup and view all the answers

Match the fabrication techniques with their descriptions:

Ion implantation = Newer method for fabricating silicon junction detectors Photolithography = Used in combination with ion implantation Complex electrode geometries = Achievable through modern fabrication methods Planar fabrication = Junction edges buried within wafer Signup and view all the answers

Match the limitations of semiconductor detectors with their descriptions:

Limitation to Small Sizes = Restricted dimensions for effective use Radiation-Induced Damage = Susceptibility due to environmental exposure Cost = Higher expense compared to alternative detectors Statistical Fluctuations = Energy resolution affected by number of carriers Signup and view all the answers

Match the factors influencing leakage current:

Minority carrier current = Roughly proportional to junction area Thermal generation = Electron-hole pairs within depletion region Surface leakage effects = Depending on encapsulation and humidity Voltage supply = Via large-value series resistor Signup and view all the answers

Match the semiconductor terms with their meanings:

Band Structure = Arrangement of energy levels in solids Discrete Electron Energy Levels = Isolated atom energy configuration Periodic Lattice = Crystalline structure regulating energy bands Allowed Energy Bands = Regions where electrons can exist in solids Signup and view all the answers

Match the terms with their effects on detector operation:

Low bias voltage = Pulse height rises with applied voltage High electric fields = Induces multiplication effects Saturation region = Pulse height no longer changes with voltage Incomplete charge collection = Trapping and recombination effects Signup and view all the answers

Match the following types of semiconductors with their characteristics:

Intrinsic Semiconductors = Pure semiconductor materials Extrinsic Semiconductors = Doped semiconductors to alter properties n-type Semiconductors = Doping with electron donors p-type Semiconductors = Doping with electron acceptors Signup and view all the answers

Match the pulse characteristics with their details:

Pulse rise time = Generally about 10ns or less Charge transit time = Critical for fast detection Detector speed = Among the fastest radiation detectors Signal integration = Involves large resistor for bias voltage Signup and view all the answers

Match the sources of leakage current with their origins:

Bulk volume = Main contributor to leakage Detector surface = Affects overall leakage Planar fabrication = Reduces surface leakage effects Cooling methods = Helpful in reducing thermal generation Signup and view all the answers

Match the electrical characteristics with their effects:

Increasing electric field = Decreases fraction of collected charge Voltage integration circuit = Used to manage leakage currents Pulse height = Continues to rise until saturation is reached Multiplication effects = Similar to gas-filled chambers Signup and view all the answers

Match the detector behavior with monitoring practices:

Monitoring leakage current = Detects abnormal behavior or damage Reduction of leakage = Achieved by cooling methods Series resistor usage = Can lead to large leakage currents Thermal generation effects = Can be minimized but not eliminated Signup and view all the answers

Match the terms related to semiconductor behavior with their correct descriptions:

Drift velocity = Velocity due to an electric field Saturation velocity = Maximum drift velocity in high fields Intrinsic semiconductor = Completely pure semiconductor Diffusion = Spread in arrival position and collection time Signup and view all the answers

Match the semiconductor types with their definitions:

Electrons = Negatively charged charge carriers Holes = Positively charged charge carriers Intrinsic = Defined solely by thermal excitation Doped = Modified by impurities to alter properties Signup and view all the answers

Match the equations to their relevant contexts in semiconductors:

$vh = , , , \mu_h , E$ = Drift velocity of holes $\rho = \frac{1}{eni(\mu_e + \mu_h)}$ = Resistivity formula $I = Ani_e(\nu_e + \nu_h)$ = Net current in semiconductors $ni = pi$ = Intrinsic carrier density equality Signup and view all the answers

Match the factors influencing conductivity in semiconductors:

Carrier density = Number of charge carriers per unit volume Mobility = Speed of charge carriers in an electric field Surface area = Size of the conducting area Thickness = Distance charge carriers travel in the material Signup and view all the answers

Match the semiconductor characteristics with their typical values:

Saturation velocity = ~$10^7$ cm/s Carrier density in Si = $1.5 , \cdot , 10^{10}/cm^3$ Carrier density in Ge = $2.4 , \cdot , 10^{13}/cm^3$ Typical diffusion spread = < 100 µm Signup and view all the answers

Match the terms to the effects observed in semiconductors:

Thermal excitation = Generates electron-hole pairs Recombination = Decreases charge carrier density Mobility = Response to the applied electric field Impurities = Modify electrical properties Signup and view all the answers

Match the mathematical principles with their correct applications in semiconductors:

$\mu = \frac{vh}{E}$ = Mobility definition $I = V/\rho$ = Ohm's law for semiconductors $\rho = R , A / L$ = Resistivity formula relationship $ni = p_i$ = Equality of electron and hole densities in intrinsic semiconductors Signup and view all the answers

Match the semiconductor conditions with their behaviors:

Low to moderate electric fields = Drift velocity proportional to electric field High electric fields = Drift velocity reaches saturation Doped semiconductors = Altered intrinsic properties Intrinsic state = Only thermal excitation causes charge carriers Signup and view all the answers

Match the following semiconductor types with their characteristics:

Intrinsic Semiconductors = Undoped and have equal electron and hole concentration N-type Semiconductors = Doped with pentavalent impurities providing extra electrons P-type Semiconductors = Doped with trivalent impurities creating holes Compound Semiconductors = Consist of two or more atomic elements Signup and view all the answers

Match the following III-V compounds with their advantages and drawbacks:

GaAs = Faster and more radiation resistant than Si GaP = Used in LED applications InP = High electron mobility GaSb = Less industrial experience than Si Signup and view all the answers

Match the following II-VI compounds with their specific properties:

CdTe = Efficient at detecting photons ZnSe = Used in blue light applications ZnS = Good for white LEDs CdS = Often used in solar cells Signup and view all the answers

Match the following terms with their definitions related to semiconductors:

Donor Impurities = Pentavalent atoms providing extra conduction electrons Fermi Level (EF) = Energy level indicating the probability of occupancy by electrons Breaking Voltage = The voltage at which a semiconductor begins to conduct Electron Mobility = The speed at which electrons move through a semiconductor material Signup and view all the answers

Match the following factors with their effect on semiconductor properties:

Bandgap = Determines the energy required for electron excitation Thermal Stability = Influences the operational temperature range Electron Mobility = Affects current flow efficiency Recombination = Decreases the number of free charge carriers Signup and view all the answers

Match the following semiconductors with their doping types:

Silicon (Si) = Can be intrinsic or extrinsic Gallium Arsenide (GaAs) = Best used in high-speed electronics Cadmium Telluride (CdTe) = Promising for photovoltaic applications Tin Dioxide (SnO2) = Commonly used as a transparent conducting oxide Signup and view all the answers

Match the following semiconductor applications with their corresponding materials:

LEDs = GaP and InP Solar Cells = CdTe and CdS High-Power Electronics = Si and III-V compounds Opto-electronics = ZnSe and InGaN Signup and view all the answers

Match the following intrinsic semiconductor characteristics with their values:

Resistance = $230,000 , ext{Ω cm}$ Carrier Concentration = $1.5 \times 10^{10} , ext{cm}^{-3}$ Electric Field Strength = $1350 + 480 , ext{cm}^2/Vs$ Temperature = Room Temperature (~300K) Signup and view all the answers

Match the following types of semiconductor detector configurations with their descriptions:

Diffused junction detectors = Treatment with n-type vapor to create a region near surface Ion implanted layers = Surface of semiconductor exposed to accelerator produced ions Surface barrier detectors = High density of electron traps at the surface of n-type crystal Partially depleted detectors = Variable active volume depending on reverse bias Signup and view all the answers

Match the following terms related to semiconductor detectors with their meanings:

Depletion region = Active volume of detector where charge carriers are collected Breakdown voltage = Maximum operating voltage before failure occurs Dead layer = Surface layer outside the depletion region that hinders detection Reverse bias = Voltage applied to enhance charge carrier collection Signup and view all the answers

Match the following features of junction detectors with their roles:

Width of depletion area = Represents the active detector volume Small detector capacitance = Needed for good energy resolution Max E-field = Occurs at the transition between p- and n-material Sensitivity to light = Causes high noise levels in thin entrance windows Signup and view all the answers

Match the following processes with their characteristics:

Diffusion = Creating n-type areas in p-type crystals Ion implantation = Controlling concentration profile through ion energy Etching = Procedure to prepare the surface of semiconductor detectors Evaporation = Method to deposit thin metal layers for electrical contact Signup and view all the answers

Match the following types of radiation detection issues with their corresponding effects:

Dead layer = Reducing efficiency of particle detection High noise levels = Resulting from light sensitivity Charge carrier collection = Efficiency dependent on depletion region Capacitance variation = Influenced by applied voltage in partially depleted detectors Signup and view all the answers

Match the following semiconductor detector characteristics with their typical values:

Max E-field = Typically $10^6 - 10^7$ V/m Depth of diffused layer = Ranges from 0.1 to 2.0 µm Thickness of gold layer = Approximately 20 nm Operating voltage = Must be below breakdown voltage Signup and view all the answers

Match the following effects related to semiconductor p-n junctions with their outcomes:

Reversed biased p-n junction = Attractive for radiation detection Creation of charge carriers = Occurs within the depletion region Active detector volume = Dependent on the reverse bias Variable capacitance = Resulting from applied voltage changes Signup and view all the answers

Match the following terms in semiconductor detector technology with their relevance:

Capacitance = Impacts charge collection efficiency Active volume = Determined by depletion region width Depletion region width = Varies with reverse bias voltage Sensitivity = Critical for detector performance and noise control Signup and view all the answers

Match the features of Ge detectors with their descriptions:

Cryostat = Inhibits thermal conductivity between crystal and surrounding air Dewar = Houses liquid nitrogen for cooling Interlock mechanism = Prevents high voltage application before low temperature is reached Preamplifier = Reduces electronic noise by being cooled Signup and view all the answers

Match the configurations of Germanium detectors with their advantages:

Closed-ended coaxial = Avoids surface leakage current Well configuration = Allows access to central hole for additional sources Rectifying contact on outer surface = Lower depletion voltage and higher electric field Thin end window = Minimizes gamma ray attenuation before entering the detector Signup and view all the answers

Match the factors affecting energy resolution in Ge detectors:

Statistical spread in charge carriers = Inherent variability in charge collection Charge collection efficiency = Influences the response of the detector Electronic noise = Contributes to overall energy measurement uncertainty Radiation energy = Affects how factors dominate energy resolution Signup and view all the answers

Match the properties of charge collection in Ge detectors with their implications:

Drift velocity = Increases linearly with electric field for low fields Saturation of drift velocity = Occurs at high electric fields Time constant in measuring electronics = Influences the leading edge of signal pulse Limiting factors for time resolution = Charge collection is inherently slow Signup and view all the answers

Match the operational characteristics of Ge detectors with their required conditions:

Ge(Li) detectors = Must maintain low temperature continuously HPGe detectors = Can be kept at room temperature between uses Room temperature operation = Impossible due to small bandgap Vacuum-tight housing = Prevents thermal conductivity issues Signup and view all the answers

Match the aspects of germanium crystal characteristics with their implications:

Limited size of crystal = Results in smaller wafer and volume Purity level of 99.99999999999% = Indicates high quality of germanium Cylindrical crystal = Allows for larger volumes of crystal Surface configuration = Impacts the electric field's radial perfection Signup and view all the answers

Match the different types of Ge detectors with their cooling strategies:

Ge(Li) detector = Requires continuous low temperature HPGe detector = Can be warmed up in between usages Traditional Ge detector = Requires cooling to 77 K Liquid nitrogen reservoir = Essential for efficient cooling of Ge detectors Signup and view all the answers

Match the components involved in the design of Germanium detectors with their roles:

Input stages of preamplifier = Cooled to reduce electronic noise Liquid nitrogen = Maintains low operational temperature Crystal configuration = Affects the planar front entrance window Electric field application = Influences overall detector performance Signup and view all the answers

Match the issues faced by Ge detectors with their solutions:

Surface leakage current = Addressed by closed-ended coaxial design Drifting of lithium = Avoided in HPGe detectors Thermal conductivity = Minimized with vacuum-tight cryostat Signal pulse timing = Managed by the equivalent circuit's time constant Signup and view all the answers

Match the environmental conditions with their impacts on Ge detectors:

High temperature = May cause catastrophic redistribution of lithium Low temperature = Necessary for stable operation of Ge(Li) Vacuum conditions = Help prevent thermal conductivity Gamma ray detection = Impacted by thin end window location Signup and view all the answers

Flashcards

Band Gap

The difference in energy between the valence band and the conduction band, crucial for determining the behavior of a material as a conductor, insulator, or semiconductor.

Energy Bands

In a solid material, the energy levels available for electrons to occupy. These levels are grouped into bands, with the valence band representing electrons bound to atoms, and the conduction band representing free-moving electrons.

Conductor

A material where electrons can move freely, with a small or nonexistent energy gap between the valence and conduction bands. This allows for easy flow of electric current.

Insulator

A material where electrons are tightly bound and do not easily move, possessing a large energy gap between the valence and conduction bands. This prevents the flow of electric current.