Abstract: A semiconductor device includes element regions which each include a first region of a first conductivity type, a second region of the first conductivity type on the first region and having a higher impurity concentration than that of the first region, a third region of a second conductivity type on the second region. The second region is between the first and third regions in a first direction. A first insulating portion surrounds each element region in a first plane. A fourth region of the first conductivity type surrounds each element region and the first insulating portion in the first plane. The fourth region has a higher impurity concentration than that of the first region. A quenching structure is above a part of the fourth region in the first direction and electrically connected to the third region.

Abstract: A semiconductor device includes a photosensitive element, an insulating region, and a quench element. The photosensitive element includes a first semiconductor region of a first conductivity type, a second semiconductor region of the first conductivity type on the first semiconductor region, a third semiconductor region of a second conductivity type on the second semiconductor region, and a fourth semiconductor region of the second conductivity type around the second and third semiconductor regions. An impurity concentration of the first conductivity type in the second semiconductor region is higher than that in the first semiconductor region. An impurity concentration of the second conductivity type in the fourth semiconductor region is lower than that of the third semiconductor region. The insulating region is around the first and fourth semiconductor regions. The quench element is electrically connected to the third semiconductor region.

Abstract: A light detector according to one embodiment includes a substrate, a plurality of avalanche photodiodes, a well region, and a microlens array. The plurality of avalanche photodiodes are provided above the substrate. Each of the avalanche photodiodes is surrounded by a trench portion among a plurality of trench portions. The well region is provided between the trench portions that are adjacent to each other. The well region includes at least one of a transistor and a diode. The microlens array is provided to cover the avalanche photodiodes.

Abstract: A semiconductor device includes element regions which each include a first region of a first conductivity type, a second region of the first conductivity type on the first region and having a higher impurity concentration than that of the first region, a third region of a second conductivity type on the second region. The second region is between the first and third regions in a first direction. A first insulating portion surrounds each element region in a first plane. A fourth region of the first conductivity type surrounds each element region and the first insulating portion in the first plane. The fourth region has a higher impurity concentration than that of the first region. A quenching structure is above a part of the fourth region in the first direction and electrically connected to the third region.

Abstract: A light detector includes an array of single-photon avalanche photodiodes (SPADs). Each of the SPADs includes an avalanche photodiode (APD), a first resistor connected in series with the APD, a second resistor connected to a node between the APD and the first resistor, a rectifying element connected in series with the second resistor between the second resistor and a constant power source, and a high-frequency current reduction circuit connected in series with the rectifying element between the rectifying element and the constant power source. The high frequency current reduction circuit is configured to reduce a high-frequency current flowing toward the constant power source when an avalanche phenomenon occurs in the APD.

Abstract: A semiconductor device includes a photosensitive element, an insulating region, and a quench element. The photosensitive element includes a first semiconductor region of a first conductivity type, a second semiconductor region of the first conductivity type on the first semiconductor region, a third semiconductor region of a second conductivity type on the second semiconductor region, and a fourth semiconductor region of the second conductivity type around the second and third semiconductor regions. An impurity concentration of the first conductivity type in the second semiconductor region is higher than that in the first semiconductor region. An impurity concentration of the second conductivity type in the fourth semiconductor region is lower than that of the third semiconductor region. The insulating region is around the first and fourth semiconductor regions. The quench element is electrically connected to the third semiconductor region.