Universal fluctuations in the growth of semiconductor thin films

Scaling of surface fluctuations of polycrystalline CdTe/Si(100) films grown by hot-wall epitaxy are studied. The growth exponent of surface roughness and the dynamic exponent of the autocorrelation function in the mound growth regime agree with the values of the Kardar-Parisi-Zhang (KPZ) class. The scaled distributions of heights, local roughness, and extremal heights show remarkable collapse with those of the KPZ class, giving an experimental observation of KPZ distributions in 2 + 1 dimensions. Deviations from KPZ values in the long-time estimates of dynamic and roughness exponents are explained by spurious effects of multipeaked coalescing mounds and by effects of grain shapes. Thus, this scheme for investigating universality classes of growing films advances over the simple comparison of scaling exponents.