III-V Heterojunction Tunnel FETs Joachim Knoch

Transcription

1 III-V Heterojunction Tunnel FETs Joachim Knoch Micro- and Nanoelectronics Devices Group Micro and Nanoelectronics Devices Group TU Dortmund University, Dortmund, Germany

2 Introduction - TFETs Operation Principle getting rid of f(e) getting rid of k B T J. Knoch, S. Mantl and J. Appenzeller, Solid-State Electron., 51, 572 (2007). J. Appenzeller, Y.-M. Lin, J. Knoch, Z. Chen and Ph. Avouris, IEEE Trans. Electron Dev. 52, 2568 (2005).

3 Introduction - TFETs Operation Principle exponential increase of I d since thinning of tunneling barrier is dominant

4 Introduction - TFETs Operation Principle point slope exponential increase of I d since thinning of tunneling barrier is dominant average slope

5 Introduction - TFETs Operation Principle band-pass filter behavior effective cooling of f(e) J. Knoch, S. Mantl and J. Appenzeller, Solid-State Electron., 51, 572 (2007).

6 Introduction - TFETs Operation Principle band-pass filter behavior effective cooling of f(e) J. Knoch, S. Mantl and J. Appenzeller, Solid-State Electron., 51, 572 (2007).

7 type II heterointerface leads to broken/staggered band alignment e.g. in InAs / Al x Ga 1-x Sb steepest possible p-n junction vertical device structure with heterointerface at nanowire / substrate interface J. Knoch, Proc Internat. Symp. VLSI-TSA, 45 (2009).

8 large source doping concentration yields high on-state current due to screening of the gate fringing fields inverse subthreshold slope always 60mV/dec in case of high source doping J. Knoch, Proc Internat. Symp. VLSI-TSA, 45 (2009). J. Knoch and J. Appenzeller, IEEE EDL, 31, 305 (2010).

9 Injecting Contact high doping level needed to screen gate impact but: large E f yields S 60mV/dec J. Appenzeller, J. Knoch, M.T. Bjoerk, H, Schmid, H. Riel and W. Riess, IEEE Trans. Electron Dev., 55, 2827 (2008).

10 Injecting Contact particularly important in III-V semiconductors with low DOS Sdegradeswith decreasing dop

11 Injecting Contact particularly important in III-V semiconductors with low DOS S degrades with decreasing dop smaller impact due to fringing is advantagous

12 Staggered versus Broken significant density of states in potential notch and inelastic scattering yield S=60mV/dec in broken case J. Knoch and J. Appenzeller, IEEE EDL, 31, 305 (2010).

13 Staggered versus Broken S=60mV/dec in the case of broken band gap optimum S=33mV/dec with staggered band line-up close to broken case and moderate doping J. Knoch and J. Appenzeller, IEEE EDL, 31, 305 (2010).

14 Staggered versus Broken S=60mV/dec in the case of broken band gap optimum S=33mV/dec with staggered band line-up close to broken case and moderate doping highest on/off-ratio at combination with steepest slope J. Knoch and J. Appenzeller, IEEE EDL, 31, 305 (2010).

15 Staggered versus Broken S=60mV/dec in the case of broken band gap optimum S=33mV/dec with staggered band line-up close to broken case and moderate doping highest on/off-ratio at combination with steepest slope for optimized device very high intrinsic performance possible J. Knoch and J. Appenzeller, IEEE EDL, 31, 305 (2010).

16 Conclusion III-V heterojunction ti TFETs allow high h on-state t performance and steep S low density of states in source requires tradeoff between high on-state and steep inverse subthreshold slope staggered band line-up yields better on/off- performance than broken case