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Static Measurements of Semiconductor Materials. Alessandra Borgia PHY651 Professor Marina Artuso December 14, 2009. Outline . Semiconductors as detectors Theoretical background Setup & Equipment Techniques Measurements Concluding remarks. Semiconductors as detectors Silicon.
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Static Measurements of Semiconductor Materials Alessandra Borgia PHY651 Professor Marina Artuso December 14, 2009
Outline • Semiconductors as detectors • Theoretical background • Setup & Equipment • Techniques • Measurements • Concluding remarks Alessandra Borgia SU Phy651 Symposium
Semiconductors as detectorsSilicon • Particle physics • Astronomy • X-ray spectroscopy • Medical physics • imaging and scanning • Etc… Alessandra Borgia SU Phy651 Symposium
Examples Pixel or Strip detector Particle track Photodiode Alessandra Borgia SU Phy651 Symposium
A bit of theory behind semiconductor sensors • Measure IV and CV curves to observe characteristics of semiconductor materials. • Diode Equation • Capacitance dependence on bias voltage • c. Depletion voltage and doping concentration • d. Bias voltage and resistivity • (with d in [μm] and ρ in [Ω*cm], in the last equation). Alessandra Borgia SU Phy651 Symposium
Current (A) Voltage(V) Ideal Diode + Resistor Curves Current (A) Voltage(V) Alessandra Borgia SU Phy651 Symposium
Ideal Capacitance Curves Capacitance (F) Voltage (V) [Ref. IV] Alessandra Borgia SU Phy651 Symposium
Experiment • Clean room in SB • Probe station • Labview programs • Power supply and meters • Sample materials • Si Tesla wafer • Hamamatsu photodiodes Alessandra Borgia SU Phy651 Symposium
Schematic Setup and Technique Ref. [V] Alessandra Borgia SU Phy651 Symposium
Initial IV Measurements What is this? There is a trend! Really? This is bad! Cause: Bad connection with probes? Sensitivity of power supply and meter? Cause: Sensitivity of power supply and meter? Alessandra Borgia SU Phy651 Symposium
Second attempt:IV Measurements Alessandra Borgia SU Phy651 Symposium
Initial CV Measurements • Results don’t make any sense! What is this? Linear?! Cause: ???? Cause: Glue between leads! Alessandra Borgia SU Phy651 Symposium
Second Attempt:CV Measurements Vdep~105V Vdep~58V Vdep~20V Alessandra Borgia SU Phy651 Symposium
An example of calculations • Tesla C region diode: • Using the following • ω = 300um • Vdep ~ 50 to 200 V • Resistivity, ρ ~ 2 to 2.5 kΩ cm • N = 2.1 x 1012 cm-3 • Measurements: • Vdep ~ 105V • N =1.54 x 1012 cm-3 • ρ = 3kΩ Alessandra Borgia SU Phy651 Symposium
Conclusion • Good experimental data is time consuming and very difficult to obtain, but worth it! • Measured important values of certain semiconductor materials, silicon. • Gained more experience in experimental techniques. • Understand more about semiconductor sensor physics. Alessandra Borgia SU Phy651 Symposium
Works Cited • Spieler, Helmuth. Semiconductor Detector Systems. Oxford University Press, NY 2005. • Lutz, Gerhard. Semiconductor Radiation Detectors. Springer, NY 1999. • Kemmer, J., et al. Current and capacitance measurements as a fast diagnostic tool for evaluation of semiconductor parameters. Nuclear Instruments and Methods in Physics Research A. 439 (2000) 199-207. • T.J.V. Bowcock. Semiconductor Detectors for Particle Physics Notes. Lausanne University, Switzerland, 2004. • Gwen Lefeuvre. Manuals for measurements in the Clean Room. Syracuse University, 2007. Alessandra Borgia SU Phy651 Symposium