Description

In this semiconductor-physics-related Immersion, participants will implement capacitance-voltage profiling on a reverse-biased Schottky barrier diode to determine the density of impurity dopants in its semiconductor layer as well as its built-in electric potential. A commercially produced Schottky diode will be used as the sample. Data acquisition and analysis will be carried out under computer-control using LabVIEW software written by the participants (however, data may also be acquired manually, if desired). Two different approaches will be available, one using research-grade instrumentation, the other using low-cost data acquisition (DAQ) devices. Ideally, participants will implement both approaches and compare the resulting accuracies of the two methods. For the low-cost setup, the phase-sensitive detection required to measure the sample’s capacitance will be carried out by implementing the lock-in detection algorithm in software. Solutions for overcoming the limitations of the DAQ device being used (e.g., restricted analog-to-digital conversion speed, inadequate waveform generation capabilities, lack of hardware triggering) will be explored. For the research-grade approach, a Stanford Research System lock-in amplifier, Keysight function generator, and DL Instruments Current Preamplifier will be used. Preferably, participant will have a background in LabVIEW programming and have experience in writing VIs that control a National Instruments DAQ device as well as VIs that communicate with a stand-alone instrument using a GPIB (or USB) interface bus. However, those with no previous LabVIEW experience, but a willingness to learn the required LabVIEW skills prior to the Immersion, the mentor can supply LabVIEW training materials for self-study.

Equipment List

Need for Both Approaches:

• 1.       Semiconix Semiconductor STPS20120D Schottky Diode (available from Digikey)
• 2.       1 nF Capacitor (for Calibration)
• 3.       Powered Breadboard

Low-Cost Approach:                                                                            

• 1.       National Instruments USB-6002 DAQ Device* ($400)
• 2.       LF411 Op-Amps
• *Other DAQ devices will also be available at the Immersion including USB-6351, USB-6009, and myDAQ.

Research-Grade Approach:

• 1.       Stanford Research Systems SR830 Lock-in Amplifier ($5250)
• 2.       Keysight 33210A Function Generator ($1480)
• 3.       DL Instruments 1211 Current Preamplifier ($4000)