Realization of wide electron slabs by polarization bulk doping in graded   III-V nitride semiconductor alloys
  We present the concept and experimental realization of polarization-induced bulk electron doping in III-V nitride semiconductors. By exploiting the large polarization charges in the III-V nitrides, we are able to create wide slabs of high density mobile electrons without introducing shallow donors. Transport measurements reveal the superior properties of the polarization doped electron distributions than comparable shallow donor doped structures. The technique is readily employed for creating highly conductive layers in many device structures. 
Debdeep Jena, Sten Heikman, Daniel Green, Ilan B. Yaacov, Robert   Coffie, Huili Xing, Stacia Keller, Steve DenBaars, James ...