We present the experimental results obtained with a novel monolithic silicon pixel detector which consists in depositing a n-i-p hydrogenated amorphous silicon (a-Si:H) diode straight above the readout ASIC (this technology is called Thin Film on ASIC, TFA). The characterization has been performed on 13 and 30μm thick a-Si:H films deposited on top of an ASIC containing a linear array of high-speed low-noise transimpedance amplifiers designed in a 0.25μm CMOS technology. Experimental results presented have been obtained with a 600nm pulsed laser. The results of charge collection efficiency and charge collection speed of these structures are discussed. © 2003 Elsevier B.V. All rights reserved.