RF and Microwave Semiconductor Technologies Muhammad Fahim Ul Haque, Department of Electrical Engineering, Linköping University muhha@isy.liu.se Note: 1. This presentation is for the course of State of the Art Electronic Devices. 2. The presentation is brief compilation of books and research papers mentioned in reference section.
Introduction Bipolar Devices Bipolar junction transistor (BJT) Hetero junction bipolar transistor (HBT) Tunnel diodes Field-effect devices Junction field effect transistor (JFET) Metal semiconductor field effect transistor (MESFET) High electron mobility transistor (HEMT) Metal oxide semiconductor field effect transistor (MOSFET) Transferred electron devices Gunn diodes LSA diodes InP diodes CdTe diodes Avalanche transit time devices IMPATT diodes TRAPATT diodes BARITT diodes Read diodes 2
Introduction Output power and operating frequency currently required for specific systems along with semiconductor materials. 3
FoM for Micro-wave Transistors Transition frequency (f T ): The frequency at which the alternating current gain becomes unity. Good figure of merit for transistor working as high speed switch. Maximum oscillation frequency (f max ) The frequency at which the unilateral power gain become unity. Good figure of merit for analog circuit. 4
5 Bipolar Junction Transistors
6 Bipolar Junction Transistors
Bipolar Junction Transistors The transition frequency f T is related to the transit time τ that is required for carrier to travel through the emitter-collector structure: f T = 1 τ This transition time is generally composed of three delays: τ = τ E + τ B + τ C The τ E base-emitter depletion region charging time, which is given as: τ E = r E C 7
Bipolar Junction Transistors The τ B is base layer charging time and it is given as: τ B = W B 2 ηd n B The τ C is the transition time through base-collector junction and it is expressed as: τ C = w C v s The f max of BJT is given as: f max = f τ 8πCC R B 8
Power-Frequency limitation of micro-wave transistors The microwave transistor have power-frequency limitation due to following reason: 1. There is a maximum possible velocity of carrier in a semiconductor. 2. There is a maximum electric field that can be sustained in a semiconductor without having dielectric break down. Based on above mentioned reason Johnson derived four basic equation for the power frequency limitation on microwave transistor 9
Power-Frequency limitation of micro-wave transistors First equation: Voltage-Frequency limitation: V m f τ = E mv s 2π Second equation: Current-Frequency limitation: I m f T = E mv s 2πX C 10
Power-Frequency limitation of micro-wave transistors Third equation: Power-Frequency limitation: (P m X C ) 1/2 f T = E mv s 2π Fourth equation: Power gain-frequency limitation: (G in V th V m ) 1/2 f max = E mv s 2π G m = f T f max 2 Zout Z in 11
f T limitation of Bipolar Junction Transistors F T increases as base length decreases. Decrease in base length results increase in base doping concentration in order to avoid punch through. This results increase in emitter doping concentration to maintain emitter injection efficiency, which in turn control the current gain. However emitter material have limited solubility of doping atom, which results finite reduction in base length. 12
Hetero junction Bipolar Transistors (HBTs) Basic structure of HBTs Energy band diagram of HBT 13
Hetero junction Bipolar Transistors (HBTs) Structure of DHBT Energy band diagram of SiGe DHBT Cross section SiGe DHBT 14
Hetero junction Bipolar Transistors (HBTs) Structure of DHBT Energy band diagram of SiGe DHBT Cross section SiGe DHBT 15
Hetero junction Bipolar Transistors (HBTs) Improvement in cutoff frequency and maximum oscillation frequency from 1999-2011 for SiGe HBTs Cutoff frequency breakdown voltage compromise and application field for SiGe HBTs 16
MOSFETs Structure of MOSFET f T = g m 2π C gs + C gd Where C gs WLC ox ; C gs WLC ox ; g m = 2μ n C ox W L I D 17
MOSFET Structure of MOSFET Problem for MOSFET downsizing and scaling method 18
MOSFETs Development of MOSFET RF technology: performance versus technological node versus year 19
MESFETs Basic Structure of MESFET f T = v sat L 20
High Electron Mobility Transistors (HEMTs) Structure of HEMET f T = v sat L Energy band Diagram of HEMET 21
High Electron Mobility Transistors (HEMTs) Structure of HEMT f T = v sat L Energy band Diagram of HEMET 22
Selected Publications Mishra, Umesh K.; Shen, L.; Kazior, T.E.; Yi-Feng Wu, "GaN-Based RF Power Devices and Amplifiers," Proceedings of the IEEE, vol.96, no.2, pp.287,305, Feb. 2008 Wu, Y. F.; Moore, M.; Saxler, A.; Wisleder, T.; Parikh, P., "40-W/mm Double Field-plated GaN HEMTs," Device Research Conference, 2006 64th, vol., no., pp.151,152, 26-28 June 2006 Komiak, J.J., "GaN HEMT: Dominant Force in High-Frequency Solid-State Power Amplifiers," Microwave Magazine, IEEE, vol.16, no.3, pp.97,105, April 2015 23
GaN HEMTs The GaN HEMT is preferred device for high frequency and high power amplification. The advantage of GaN HEMT are as follows: High output power density High impedance High output voltage 24
GaN HEMTs Structure of Typical GaN HEMT DC and pulse I-V characteristics of typical GaN HEMT Structure of unpassivated GaN HEMT 25
Gate Connected Field-Plate GaN HEMT Structure of gate-connected field plate GaN HEMET Power density vs drain voltage for various FP length. Device dimension: 0.5x246 μm 26
Gate Connected Field-Plate GaN HEMT Power performance of GaN HEMTs with gate-connected field plate f t and f max as function of FP length L 27
Source Connected Field-Plate GaN HEMT Structure of gate-connected field plate GaN HEMET MSG as a function of drain voltage 28
Source Connected Field-Plate GaN HEMT Power sweeps with SC-FP device and GC-FP. (Device dimension 0.5x500 μm) 29
Double Field-Plate GaN HEMT Structure of double field plate GaN HEMET. Power sweep of a double field-plated GaN HEMT. 30
Double Field-Plate GaN HEMT Comparison of MSG and maximum operation voltage at 10GHz for various device design. 31
Deep-Recessed GaN HEMTs Structure of deep-recessed GaN HEMET. Power performance of a deep-recessed GaN HEMT. 32
GaN MOSHEMTs Structure of deep-recessed GaN HEMET. Gate-leakage currents for MOSHEMT gate at different temperature and the baselime HEMT at room temprature. 33
GaN MOSHEMTs Maximum saturation and gateleakage currents in MOSHEMT and HEMT devices Power sweep at 2 GHz for 200 μm wide MOSHEMT device. 34
GaN MOSHEMTs Maximum saturation and gateleakage currents in MOSHEMT and HEMT devices Power sweep at 2 GHz for 200 μm wide MOSHEMT device. 35
Summary Amplifier power and frequency bench marks 36
References [1] Joachim N. Burghartz (ed), Guide to state-of-the-art electron devices, IEEE Press 2013. [2] Samuel Y. Liao, Microwave devices and circuits, 3 rd Edition, Pearson Education Limited 2003. [3] Reinhold Ludwig and Pavel Bretchko, RF circuit design theory and applications, Pearson Education Limited 2000. [4] Mishra, Umesh K.; Shen, L.; Kazior, T.E.; Yi-Feng Wu, "GaN-Based RF Power Devices and Amplifiers," Proceedings of the IEEE, vol.96, no.2, pp.287,305, Feb. 2008. [5] Wu, Y. F.; Moore, M.; Saxler, A.; Wisleder, T.; Parikh, P., "40-W/mm Double Fieldplated GaN HEMTs," Device Research Conference, 2006 64th, pp.151,152, 26-28 Jun. 2006. [6] Komiak, J.J., "GaN HEMT: Dominant Force in High-Frequency Solid-State Power Amplifiers," Microwave Magazine, IEEE, vol.16, no.3, pp.97,105, Apr. 2015. [7] Kasu, M.; Diamond field-effect transistor as microwave power amplifier, NTT Technical Review, vol. 8, no. 8, Aug. 2010. [8] Gerhard Klimeck (2012), "ECE 606 Lecture 20: Heterojunction Bipolar Transistor," https://nanohub.org/resources/15715. 37
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