Shot noise in transport through quantum dots: Clean versus disordered samples

We investigate the role of disorder and diffractive scattering in the shot noise power of quantum transport through a two-dimensional quantum dot. By tuning the strength of the disorder potential and the openings of the dot, we numerically explore the influence of quantum scattering mechanisms on the current shot noise. For small cavity openings we find the shot noise for disordered samples to be of almost equal magnitude as for clean samples where transport is ballistic. We explain this finding by diffractive scattering at the cavity openings which act as strong noise sources. Estimates for the shot noise induced by both the disorder potential and the diffractive openings are presented that agree with the numerical data.