Zhores Alferov shared the 2000 Nobel Prize in Physics "for basic work on information and communication technology.” Alferov won half the prize jointly with Herbert Kroemer "for developing semiconductor heterostructures used in high-speed- and opto- electronics.” They shared the prize with Jack S. Kilby who won "for his part in the invention of the integrated circuit." Alferov and Kroemer independently applied double heterostructures to laser light. A heterostructure is a boundary between different materials (usually both semiconducting materials) that restricts the charge carriers because the different materials have different allowed energy levels. A double heterostructure is one that has one type of semiconducting material surrounded by another type of semiconducting material, creating two boundaries with mismatched energy levels. Alferov also created the heterotransistor that could be used with higher frequencies than common transistors of the time, and greatly advanced cell phone and satellite communications.