California Institute of Technology

Arizona State University

Philippe C Adell

Harry A Atwater

Bertan Bakkaloglu

Hugh Barnaby

Ming Sun

Tao Liu

Blayne Tolleson

Bert Vermeire

Harry A Atwatere

The disclosed technology generally relates to characterization of semiconductor structures, and more particularly to optical characterization of high-k dielectric materials. A method includes providing a semiconductor structure comprising a semiconductor and a high-k dielectric layer formed over the semiconductor, wherein the dielectric layer has electron traps formed therein. The method additionally includes at least partially transmitting an incident light having an incident energy through the high-k dielectric layer and at least partially absorbing the incident light in the semiconductor. The method additionally includes measuring a nonlinear optical spectrum resulting from the light having the energy different from the incident energy, the nonlinear optical spectrum having a first region and a second region, wherein the first region changes at a different rate in intensity compared to the second region. The method further includes determining from the nonlinear optical spectrum one or both of a first time constant from the first region and a second time constant from the second region, and determining a trap density in the high-k dielectric layer based on the one or both of the first time constant and the second time constant.

Optical systems and methods of characterizing high-k dielectrics

The disclosure describes a method for modeling excess base current in irradiated bipolar junction transistors (BJTs). The method includes quantifying defect-related electrostatic effects of a BJT device to help improve accuracy in predicting an irradiated excess base current of the BJT device. The method can be adapted to model the excess base current of a lateral P-type-N-type-P-type (LPNP) BJT device in depleted and/or accumulated surface potential states. The predicted excess base current may be used to qualify or disqualify the BJT device or an electrical circuit including the BJT device for use in a space system(s) as a commercial-off-the-shelf (COTS) component. By modeling the excess base current based on quantifying and utilizing the defect-related electrostatic effects, it may be possible to accurately predict a total-ionizing-dose (TID) response of the BJT device, thus enabling faster and lower-cost qualification of a COTS component(s) for use in the space system(s).

Method for modeling excess current in irradiated bipolar junction transistors

An autozeroed comparator controls a frequency fof the input voltage inputted to a DC/DC converter. A digital frequency synchronization circuit is connected to the autozeroed comparator so as to form a phase locked loop, wherein the DES circuit controls the hysteretic window of the autozeroed comparator so as to lock fto a clock reference frequency. A plurality of slave phase circuits may be connected to the master phase circuit including the DFS circuit and the autozeroed comparator. Duty cycle calibration circuits adjust a duty cycle signal applied to each of the slave phase circuits, in response to average current measured in the slave phase circuits, so that each slave phase circuit is synchronized with the master phase circuit. A 6 A 90.5% peak efficiency 4-phase hysteretic quasi-current-mode buck converter is provided with constant frequency and maximum &#xb1;1.5% current mismatch between the slave phases and the master phase.

Digital multiphase hysteretic point-of-load DC/DC converter

A DC-DC converter for generating a DC output voltage includes: a digitally controlled pulse width modulator (DPWM) for controlling a switching power stage to supply a varying voltage to an inductor; and a digital voltage feedback circuit for controlling the DPWM in accordance with a feedback voltage corresponding to the DC output voltage, the digital voltage feedback circuit including: a first voltage controlled oscillator for converting the feedback voltage into a first frequency signal and to supply the first frequency signal to a first frequency discriminator; a second voltage controlled oscillator for converting a reference voltage into a second frequency signal and to supply the second frequency signal to a second frequency discriminator; a digital comparator for comparing digital outputs of the first and second frequency discriminators and for outputting a digital feedback signal; and a controller for controlling the DPWM in accordance with the digital feedback signal.

Growing community of inventors

Pasadena, CA, United States of America

Philippe C Adell