Wigner crystallization and metal-insulator transition of two-dimensional holes in GaAs at B=0

We report the transport properties of a low disorder two-dimensional hole s ystem (2DHS) in the GaAs/AlGaAs heterostructure, which has an unprecedented ly high peak mobility of 7 x 10(5) cm(2)/V s, with a hole density of 4.8 x 10(9) < p < 3.72 x 10(10) cm(-2) in the temperature range of 50 mK < T < 1. 3 K. From their T, p, and electric field dependences, we find that the meta l-insulator transition in zero magnetic field in this exceptionally clean 2 DHS occurs at r(s) = 35.1 +/- 0.9, which is in good agreement with the crit ical r(s) for Wigner crystallization r(s)(c) = 37 +/- 5, predicted by Tanat ar and Ceperley for an ideally clean 2D system.