wavy transistors

What is the status of out-of-plane 3D multi-gate transistors?

While out-of-plane 3D Tri-gate field effect transistors are allowing Moore's Law to continue for logic applications, for sub-10 nm node, we believe by integrating 3-D nonplanar fins and 2-D ultrathin bodies, wavy architecture FinFETs can merge two formerly competing technologies on a silicon-on-insulator platform to deliver enhanced transistor performance compared with conventional trigate FinFETs with unprecedented levels of chip-area efficiency. This makes it suitable for ultralarge-scale integration high-performance logic at and beyond the 10-nm technology node. 

H. M. Fahad, C. C. Hu, M. M. Hussain

Simulation Study of a 3D Device Integrating FinFET and UTBFET 

Published in: IEEE Transactions on Electron Devices ( Volume: 62, Issue: 1, Jan. 2015 ), Page(s): 83 - 87

DOI: 10.1109/TED.2014.2372695

How unique is the wavy architecture concept?

Inspired by the concept and effectiveness of FinFET, we reported a wavy channel FinFET like transistor where the channel is wavy to increase its width without any area penalty and thereby increasing its drive current. Through simulation and experiments, we show the effectiveness of such device architecture is capable of high performance operation compared to conventional FinFETs with comparatively higher area efficiency and lower chip latency as well as lower power consumption. 

H. M. Fahad, A. M. Hussain, G. A. Torres Sevilla, M. M. Hussain

Wavy channel transistor for area efficient high performance operation

Appl. Phys. Lett. 102, 134109 (2013); https://doi.org/10.1063/1.4800234 

Is wavy architecture compatible and effective for thin film transistor applications?

We reported an atomic layer deposition based zinc oxide channel material integrated thin film transistor using wavy channel architecture allowing expansion of the transistor width in the vertical direction using the fin type features. The experimental devices show area efficiency, higher normalized output current, and relatively lower power consumption compared to the planar architecture. This performance gain is attributed to the increased device width and an enhanced applied electric field due to the architecture when compared to a back gated planar device with the same process conditions. 

Zinc oxide integrated area efficient high output low power wavy channel thin film transistor

A. N. Hanna, M. T. Ghoneim, R. R. Bahabry, A. M. Hussain, M. M. Hussain

Appl. Phys. Lett. 103, 224101 (2013); https://doi.org/10.1063/1.4836235

Can the wavy thin film transistor be used for display technology?

We demonstrated a new thin film transistor (TFT) architecture that allows expansion of the device width using continuous fin features – termed as wavy channel (WC) architecture. This architecture allows expansion of transistor width in a direction perpendicular to the substrate, thus not consuming extra chip area, achieving area efficiency. The devices have shown for a 13% increase in the device width resulting in a maximum 2.5× increase in ‘ON’ current value of the WCTFT, when compared to planar devices consuming the same chip area, while using atomic layer deposition based zinc oxide (ZnO) as the channel material. The WCTFT devices also maintain similar ‘OFF’ current value, ∼100 pA, when compared to planar devices, thus not compromising on power consumption for performance which usually happens with larger width devices. This work offers an interesting opportunity to use WCTFTs as backplane circuitry for large-area high-resolution display applications. 

Hanna, A. N., Torres Sevilla, G. A., Ghoneim, M. T., Hussain, A. M., Bahabry, R. R., Syed, A. and Hussain, M. M. (2014), Wavy channel thin film transistor architecture for area efficient, high performance and low power displays. Phys. Status Solidi RRL, 8: 248–251. doi:10.1002/pssr.201308282 

Can the wavy thin film transistors enabled display be energy efficient?

Increased output current while maintaining low power consumption in thin-film transistors (TFTs) is essential for future generation large-area high-resolution displays. Here, we showed wavy channel (WC) architecture in TFT that allows the expansion of the transistor width in the direction perpendicular to the substrate through integrating continuous fin features on the underlying substrate. This architecture enables expanding the TFT width without consuming any additional chip area, thus enabling increased performance while maintaining the real estate integrity. The experimental WCTFTs show a linear increase in output current as a function of number of fins per device resulting in 3.5× increase in output current when compared with planar counterparts that consume the same chip area. The new architecture also allows tuning the threshold voltage as a function of the number of fin features included in the device, as threshold voltage linearly decreased from 6.8 V for planar device to 2.6 V for WC devices with 32 fins. This makes the new architecture more power efficient as lower operation voltages could be used for WC devices compared with planar counterparts. It was also found that field effect mobility linearly increases with the number of fins included in the device, showing almost 1.8× enhancements in the field effect mobility than that of the planar counterparts. This can be attributed to higher electric field in the channel due to the fin architecture and threshold voltage shift. 

A. N. Hanna, M. T. Ghoneim, R. R. Bahabry, A. M. Hussain, H. M. Fahad, M. M. Hussain

Area and Energy Efficient High-Performance ZnO Wavy Channel Thin-Film Transistor

Published in: IEEE Transactions on Electron Devices ( Volume: 61, Issue: 9, Sept. 2014 ) Page(s): 3223 - 3228

DOI: 10.1109/TED.2014.2336863 

Can low thermal budget process compatible wavy thin film transistors enhance our visualization experience?

A novel wavy-shaped thin-film-transistor (TFT) architecture, capable of achieving 70% higher drive current per unit chip area when compared with planar conventional TFT architectures, is reported for flexible display application. The transistor, due to its atypical architecture, does not alter the turn-on voltage or the OFF current values, leading to higher performance without compromising static power consumption. The concept behind this architecture is expanding the transistor's width vertically through grooved trenches in a structural layer deposited on a flexible substrate. Operation of zinc oxide (ZnO)-based TFTs is shown down to a bending radius of 5 mm with no degradation in the electrical performance or cracks in the gate stack. Finally, flexible low-power LEDs driven by the respective currents of the novel wavy, and conventional coplanar architectures are demonstrated, where the novel architecture is able to drive the LED at 2 × the output power, 3 versus 1.5 mW, which demonstrates the potential use for ultrahigh resolution displays in an area efficient manner. 

A. N. Hanna, A. T. Kutbee, R. C. Subedi, B. Ooi, M. M. Hussain 

Wavy Architecture Thin-Film Transistor for Ultrahigh Resolution Flexible Displays

Small 2017, 1703200. https://doi.org/10.1002/smll.201703200 

Are wavy thin film transistors useful for digital circuits?

High-performance thin film transistor (TFT) can be a great driving force for display, sensor/actuator, integrated electronics, and distributed computation for the Internet of Everything applications. While semiconducting oxides, such as zinc oxide (ZnO), present promising opportunity in that regard, still wide area of improvement exists to increase the performance further. Here, we showed a wavy channel (WC) architecture for ZnO integrated TFT, which increases transistor width without chip area penalty, enabling high performance in material agnostic way. We further demonstrate digital logic NAND circuit using the WC architecture and compare it with the conventional planar architecture. The WC architecture circuits have shown 2× higher peak-to-peak output voltage for the same input voltage. They also have 3× lower high-to-low propagation delay times, respectively, when compared with the planar architecture. The performance enhancement is attributed to both extra device width and enhanced field-effect mobility due to higher gate field electrostatics control. 

A. N. Hanna, A. M. Hussain, H. Omran, S. Alsharif, K. N. Salama, M. M. Hussain

Zinc Oxide Integrated Wavy Channel Thin-Film Transistor-Based High-Performance Digital Circuits

Published in: IEEE Electron Device Letters ( Volume: 37, Issue: 2, Feb. 2016 ), Page(s): 193 - 196

DOI: 10.1109/LED.2015.2505613 

Can Wavy thin film transistors be used for extended digital circuitry?

We reported a wavy channel (WC) architecture thin-film transistor-based digital circuitry using ZnO as a channel material. The novel architecture allows for extending device width by integrating vertical finlike substrate corrugations giving rise to 50% larger device width, without occupying extra chip area. The enhancement in the output drive current is 100%, when compared with conventional planar architecture for devices occupying the same chip area. The current increase is attributed to both the extra device width and 50% enhancement in field-effect mobility due to electrostatic gating effects. Fabricated inverters show that WC inverters can achieve two times the peak-to-peak output voltage for the same input when compared with planar devices. In addition, WC inverters show 30% faster rise and fall times, and can operate up to around two times frequency of the planar inverters for the same peak-to-peak output voltage. WC NOR circuits have shown 70% higher peak-to-peak output voltage, over their planar counterparts, and WC pass transistor logic multiplexer circuit has shown more than five times faster high-to-low propagation delay compared with its planar counterpart at a similar peak-to-peak output voltage. 

A. N. Hanna, A. M. Hussain, H. Omran, S. M. Alsharif, K. N. Salama, M. M. Hussain

Wavy Channel TFT-Based Digital Circuits

Published in: IEEE Transactions on Electron Devices ( Volume: 63, Issue: 4, April 2016 ), Page(s): 1550 - 1556

DOI: 10.1109/TED.2016.2527795 

INVITED REVIEW: Wavy Channel TFT Architecture for High Performance Oxide Based Displays

We chronicle the effectiveness of wavy channel architecture for thin film transistor application for increased output current. This specific architecture allows increased width of the device by adopting a corrugated shape of the substrate without any further real estate penalty. The performance improvement is attributed not only to the increased transistor width, but also to enhanced applied electric field in the channel due to the wavy architecture. 

A. N. Hanna, A. M. Hussain, M. T. Ghoneim, J. P. Rojas, G. A. Torres Sevilla, M. M. Hussain

ECS Trans. 2015 volume 67,issue 1, 191-198 

doi: 10.1149/06701.0191ecst