John A Grisham

Title: Innovations by John A Grisham

Introduction

John A Grisham is a notable inventor based in Rogersville, Alabama. He has made significant contributions to the field of semiconductor technology, holding three patents that showcase his innovative spirit and technical expertise.

Latest Patents

One of his latest patents is a device and method for performing an optical Hall test. This invention provides a means for non-destructive measurement of free carrier concentration or effective mass in semiconductor materials using Faraday rotation spectra. The device utilizes a beam emitted by a Fourier transform infrared (FTIR) spectrometer, which is transmitted through a sample mounted between a polarizer and analyzer, and the opposite poles of a magnet before being detected. The ratio of the sample's transmission spectrum with the magnetic field on to that with the magnetic field off is converted through a mathematical formula to Faraday rotation. The resulting graph plots rotation versus the square of the wavelength, allowing for the determination of carrier concentration and effective mass.

Another significant patent is the modulated high sensitivity infrared polarimeter. This invention produces a modulated Faraday rotation signal by passing a linearly polarized laser beam through a semiconductor wafer sample in a modulated magnetic field. The magnetic field is induced in an electromagnet by a sine wave generator and driver. The rotation signal is normalized by dividing it by a transmission signal produced by modulating the beam with a chopper operating at a different frequency. This results in a Faraday rotation measurement with a high signal-to-noise ratio and compensation for laser drift in intensity.

Career Highlights

John A Grisham works for the US Government as represented by the Secretary of the Army. His role involves applying his innovative ideas to advance technology in the defense sector. His work has been instrumental in enhancing the understanding and measurement of semiconductor materials.

Collaborations

Throughout his career, John has collaborated with notable colleagues such as Frederick W Clarke and Charles R Christensen. These collaborations have contributed to the development of his patents and the advancement of semiconductor technology.

Conclusion

John A Grisham is a distinguished inventor whose work in semiconductor technology has led to significant advancements. His patents reflect his commitment to innovation and his contributions to the field will have lasting impacts.