Short Channel Quantum Dot Vertical and Lateral Phototransistors

Quantum dot (QD) devices have been studied extensively as a significant platform for optoelectronic applications and photodetection, but the high efficient conversion from light to current requires high operating voltages, and has become a roadblock in a wide range of on chip applications. The main challenges rely on promoting light absorption and transportation efficiency, which occur in the same place—the channel. Here, the authors present short channel (SC) field effect phototransistors (FEpTs) by combing the QDs with the vertical architecture for the first time. These devices exhibit excellent performances in ultrahigh R of 1 × 10⁵ A W⁻¹, D* of 1.6 × 10¹³ Jones, effective quantum efficiency of 2.6 × 10⁷% at low operating voltage of ±4 V under room temperature, and they strongly depend on channel length. It is found there was an optimal L to obtain high performances, due to the two roles of channel, light harvesting, and electric transportation, which give the negative and positive contributions to photocurrent, respectively. These SC QVFEpTs exhibit a great application in photodetection, from visible to infrared, moreover, the all‐solution fabricating process and lateral detection (determined by vertical architecture) provide a convenient pathway for low cost, integrated circuit architectural compatibility.