Shot noise at the quantum point contact in InGaAs heterostructure

We study the shot noise at a quantum point contact (QPC) fabricated in an InGaAs/InGaAsP heterostructure, whose conductance can be electrically tuned by the gate voltages. Shot noise suppression is observed at the conductance plateau of $N(2e2/h)$ (N = 4,5,and 6), which indicates the coherent quantized channel formation in the QPC. The electron heating effect generated at the QPC explains the deviation of the observed Fano factor from the theory.