Thin-Film Heterojunction FETs on Poly-Si Substrates for High-Stability Driving and Low-Power Amplification

A Low-Power Thin-Film Si Heterojunction FET Noise Amplifier for Generation of True Random Numbers

“…The amplifier gain and therefore power consumption are expected to improve with the optimization of the integration process. Given the high stability of the HJFETs [10], [11], the amplifier gain is expected to be sufficiently stable over time. We believe integration of additional circuitry (such as a comparator, or sample and hold) for a monolithic random number generator is also feasible with HJFETs.…”

“…The a-Si:H and hydrogenated crystalline Si (c-Si:H) layers are grown by plasma-enhanced chemical vapor deposition (PECVD) at ∼200 • C. Despite the low process temperature, HJFETs have a high electrical stability due to the high quality of the a-Si:H/ c-Si interface. HJFETs may also be fabricated on poly-Si substrates [11]. If poly-Si is prepared by pulsed laser crystallization, HJFETs are expected to be compatible with flexible plastic substrates.…”

Electrical Stability and Flicker Noise of Thin-Film Heterojunction FETs on Poly-Si Substrates

“…The a-Si:H and c-Si:H layers are grown in the same PECVD reactor at 200 • C. The c-Si:H layer has a resistivity of ∼5×10 −4 .cm. The ∼50 nm-thick etch-stop oxide layer is also grown by PECVD at ∼200 • C. Further details regarding the fabrication process are available in [4].…”

“…The gate and source/drain regions of the HJFETs are formed by low-temperature (∼200 • C) plasma-enhanced chemical vapor deposition (PECVD) of a-Si:H and hydrogenated crystalline Si (c-Si:H), respectively. The c-Si substrate may be polycrystalline [4], in which case the c-Si:H source/drain regions are also polycrystalline, due to the epitaxial growth of c-Si:H [5], [6]. Provided that the starting poly-Si substrates are also prepared by a low-temperature technique, such as excimer laser annealing (ELA) of doped a-Si:H, the HJFET process is compatible with low-cost flexible plastic substrates.…”

“…In this paper, the electrical stability and flicker noise of HJFET devices fabricated on small-grain poly-Si substrates [4] are investigated and benchmarked against conventional TFTs. High TFT stability is critical for applications such as active-matrix organic LED (AMOLED) displays [7]- [15], while low TFT flicker noise is critical for applications such as image sensors, amplifiers, and biosensors [16]- [20].…”