Light detection device

A light detection device comprising:

• a semiconductor light detection element including a semiconductor substrate including first and second principal surfaces opposed to each other, a plurality of avalanche photodiodes operating in Geiger mode and formed in the semiconductor substrate, and first electrodes electrically connected to the respective avalanche photodiodes and arranged on the second principal surface side of the semiconductor substrate:
• a mounting substrate including a third principal surface opposed to the second principal surface of the semiconductor substrate, and a plurality of second electrodes arranged corresponding to the respective first electrodes on the third principal surface side, the mounting substrate being, arranged as opposed to the semiconductor light detection element;
• and
• quenching circuits electrically connected to the respective second electrodes,
• wherein the first electrodes and the second electrodes corresponding to the first electrodes are electrically connected through bump electrodes, and
• wherein the quenching circuits are not arranged on the semiconductor substrate of the semiconductor light detection element.