Fabrication of polycrystalline thin films by pulsed laser processing
AssigneeThe Regents of the University of California
InventorsFred Mitlitsky, Joel B. Truher, James L. Kaschmitter, Nicholas J. Colella
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Abstract
A method for fabricating polycrystalline thin films on low-temperature (or high-temperature) substrates which uses processing temperatures that are low enough to avoid damage to the substrate, and then transiently heating select layers of the thin films with at least one pulse of a laser or other homogenized beam source. The pulse length is selected so that the layers of interest are transiently heated to a temperature which allows recrystallization and/or dopant activation while maintaining the substrate at a temperature which is sufficiently low to avoid damage to the substrate. This method is particularly applicable in the fabrication of solar cells.
Claims18
A method for fabricating polycrystalline thin films including the steps of:
- forming a film of material on a substrate in a time period such that the temperature of the substrate is not raised above a temperature of about 450.degree. C. for a time period greater than about 100 .mu.s;
- and
- irradiating at least a portion of the thus formed film with at least one energy pulse to cause heating and recrystallization of at least a portion of the material of the film in a time period such that the temperature of the substrate is not raised above a temperature of about 180.degree. C. for said time period of greater than about 100 .mu.s.
A method for fabricating thin films for use in solar cells, including the steps of:
- forming at least one film of material on a substrate at a temperature of not greater than about 450.degree. C.;
- and
- directing at least one pulse of laser radiation onto at least a portion of the at least one film for causing recrystallization and increased crystal grain size of the film material without raising the temperature of the substrate above about 180.degree. C. for longer than about 100 .mu.s.
Dependencies are inferred from the claim text.