Semiconductor device comprising a divided photodiode, method of making the same, and corresponding optical pickup device

摘要

A photodiode (PD) having an anode region (4) of a first conductivity type forming a main pn junction (J) with a cathode region (9) of a second conductivity type, wherein a semiconductor region (40) of said second conductivity type disposed in said cathode region (9) and suitable for dividing the photodiode into separate photodiode portions is such that said photodiode portions are fully isolated from each other only by the combined depletion layer (41) extending, under a certain reverse bias, from both said main pn junction (J) and the pn junction (j) defined between the cathode region (9) and said dividing semiconductor region (40). Therefore, carriers generated between the photodiode portions are not deflected by the dividing semiconductor region but move directly to the depletion layer, whereby frequency characteristics are improved. In a preferred embodiment the dividing semiconductor region (40) does not extend to the anode region (4) from a surface of the cathode region (9). In further embodiments the dividing semiconductor region (40) is provided as a buried layer. The divided photodiode (PD) may be integrated with a bipolar transistor (TR). The divided photodiode (PD1,PD2) may furthermore be comprised in a semiconductor device (52) included in an optical pickup device having a light-emitting device (51) and an optical system (53).