Punch through effect enhanced type silicon photo transistor

Abstract

The invention relates to a punch through effect enhanced type silicon photo transistor which comprises two types which are a NPN type and a PNP type; the silicon photo transistor sequentially comprises a silicon substrate layer, a P pit (or a N pit) layer positioned on the silicon substrate layer, two discrete N type (or P type) heavy doping active areas positioned inside the P pit (or a N pit) layer, a field silicon dioxide layer surrounded by the two N type (or P type) heavy doping active areas, two discrete bar-shaped gate oxide silicon dioxide layers which are arranged at the narrow side of the P pit (or a N pit) layer and on the upper surface of the field silicon dioxide layer, two discrete polysilicon layers that are coated on the gate oxide silicon dioxide layers and have the same shapes as that of the gate oxide silicon dioxide layers, and a bar-shaped metallic electrode layer that is positioned on the upper surface at the wide side of the P pit (or a N pit) layer and is respectively connected with the two discrete N type (or P type) heavy doping active areas from bottom to top. The device can effectively improve photoelectric conversion gain of devices, limit the dark current of devices, and reduce the noise of devices, so as to obtain higher signal-to-noise.

Description

technical field [0001] The invention belongs to the field of semiconductor optoelectronic devices, in particular to a silicon phototransistor with punch-through effect enhancement. Background technique [0002] Semiconductor photodetectors have been widely used due to their excellent performance, tiny size and cheap price, and have penetrated into all aspects of society such as industrial and agricultural production, military technology, daily civilian use, and consumer electronics. Silicon photodetectors are a large class of semiconductor photodetectors. At present, silicon photodetectors that are widely used mainly include PIN photodiodes, APD avalanche photodiodes, and ordinary phototransistors. These photodetectors have disadvantages such as large size, high requirements on the performance of manufacturing materials, high operating voltage, incompatibility between manufacturing process and CMOS process, and difficulty in integrating with peripheral circuits. [0003] T...

AI Technical Summary

Problems solved by technology

Due to the recombination of the two-terminal phototransistor in the space charge region at the base-emitter PN junction, when the incident light power is very low, the gain is very low; in addition, the low incident light power also causes the charging time of the emitter junction capacitance to be very short Long, so the gain-bandwidth product and SNR become very small, which limits the high-speed application of this phototransistor

[0004] Although the three-terminal phototransistor has achieved some success in improving the gain and response speed, the shot noise introduced by the base bias current is also amplified by the transistor at the same time. Therefore, when the base current is much larger than the photogenerated current, the SNR will change. is very low, which severely limits the detection sensitivity of the three-terminal phototransistor in low-light conditions

Silicon through-base phototransistors not only have high gain and fast response rate performance, but also overcome the shortcomings of compound through-base phototransistors that are difficult to integrate

However, whether it is a compound substrate or a silicon substrate through base phototransistor, their dark current is relatively large, and they are not fully compatible with standard commercial CMOS processes.

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