Ultrafast optical technique for the characterization of altered materials

A method for examining a semiconductor sample having at least one localized region underlying a surface into which a chemical species may have been introduced, comprising the steps of:

• generating optical pump pulses having a wavelength selected for generating a population of charge carriers in the sample, the charge carriers diffusing within and recombining in the sample and the localized region and inducing at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample;
• measuring a response of the sample to an optical probe beam at least during a time that the optical constants are varying;
• and
• associating the measured response with at least one of chemical species concentration, chemical species type, implant energy, a presence or absence of an introduced chemical species region at the location, and a presence or absence of implant-related damage.

A method for examining a semiconductor sample having at least one localized region underlying a surface into which a chemical species has been implanted, comprising the steps of:

• thermally annealing the sample to reduce or eliminate implant-related damage;
• generating optical pump pulses having a wavelength selected for generating a population of charge carriers in the sample, the charge carriers diffusing in the sample and localized region and recombining at different rates in the sample and the localized region, the charge carriers inducing at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample;
• measuring a response of the sample to an optical probe beam at least during a time that the optical constants are varying;
• and
• determining, in accordance with the measured response, whether the sample has been sufficiently thermally annealed to reduce or eliminate the implant-related damage.

A method for examining a semiconductor sample having at least one region underlying a surface into which a chemical species has been implanted, comprising the steps of:

• generating optical pump pulses having a wavelength selected for generating a population of charge carriers in the sample, the charge carriers diffusing in the sample and localized region and recombining at different rates in the sample and the localized region, the charge carriers inducing at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample, individual ones of the optical pump pulses also launching a propagating mechanical wave in the sample;
• measuring a response of the sample to an optical probe beam at least during a time that the optical constants are varying, the measured response including an oscillatory component due to the propagating mechanical wave;
• and
• determining, in accordance with the measured response, at least one characteristic associated with the implanted region.