Jie Wei Lai

Vertical scaling of 0.25-μm emitter InP/InGaAs single heterojunction bipolar transistors with f/sub T/ of 452 GHz

Vertical scaling of the epitaxial structure has allowed submicron InP/InGaAs-based single heterojunction bipolar transistors (SHBTs) to achieve record high-frequency performance. The 0.25/spl times/16 /spl mu/m/sup 2/ transistors, featuring a 25-nm base and a 100-nm collector, display current gain cut-off frequencies f/sub T/ of 452 GHz. The devices operate at current densities above 1000 kA/cm/sup 2/ and have BV/sub CEO/ breakdowns of 2.1 V. A detailed analysis of device radio frequency (RF) parameters, and delay components with respect to scaling of the collector thickness is presented.

Submicron InP-InGaAs single heterojunction bipolar transistors with f/sub T/ of 377 GHz

Submicron InP-InGaAs-based single heterojunction bipolar transistors (SHBTs) are fabricated to achieve record-breaking speed performance using an aggressively scaled epitaxial structure coupled with a submicron emitter process. SHBTs with dimensions of 0.35 /spl times/16 /spl mu/m have demonstrated a maximum current gain cutoff frequency f/sub T/ of 377 GHz with a simultaneous maximum power gain cutoff frequency f/sub MAX/ of 230 GHz at the current density Jc of 650 kA/cm/sup 2/. Typical BV/sub CEO/ values exceed 3.7 V.

Self-aligned InP DHBTs for 150 GHz digital and mixed signal circuits

A production oriented manufacturing process for Indium Phosphide double-heterojunction bipolar transistor (DHBT) devices that enables 150 GHz digital and mixed signal circuits is presented. These transistors have cut-off frequency (f) and maximum oscillation frequency (f/sub max/) both over 300 GHz and open-base breakdown voltage (BV/sub ceo/) over 4 V. Common Mode Logic (CML) ring oscillators have exhibited 1.95 ps gate delay and Emitter Coupled Logic (ECL) static frequency dividers that operate up to 152 GHz have been demonstrated to benchmark this InP process technology. A 4:1 multiplexer for 100 Gb/s circuits is discussed along with a Gilbert cell Variable Gain Amplifier with excess of 50 GHz bandwidth and record gain bandwidth product of 397 GHz.

Design of variable gain amplifier with gain-bandwidth product up to 354 GHz implemented in InP-InGaAs DHBT technology

A high-gain and wide-band variable gain amplifier (VGA) is developed using 300-GHz InP-InGaAs double-heterojunction bipolar transistor (DHBT). Negative-R/sub E/ quad is used to enhance amplifier gain-bandwidth product. At maximum gain, the single-ended S/sub 21/ of 17 dB and the associated 3-dB bandwidth of 50 GHz are measured to produce a gain-bandwidth product of 354 GHz in a VGA including a Gilbert multiplier and an output driver. The gain-bandwidth product is twice the value measured from the VGA designed by single resistor degeneration in the same process. The circuit is designed in terms of detailed stability considerations and the experimental results show it to be unconditionally stable over 0.5-50 GHz. The linearity of the VGA is affected by nonlinear effects in DHBTs, and different design approaches are analyzed. An output interception point of the third harmonic of 16.2 dBm is measured.

300 GHz InP DHBT large signal model including current blocking effect and validated by Gilbert multiplier circuits

This paper describes a modeling approach for Vitesse VIP2 300 GHz InP/InGaAs DHBT technology, including the nonlinear effects in base-collector region covering current blocking, velocity modulation and self-heating. Model is verified in terms of single devices and integrated circuits. Good model fitting to measured DC and S-parameters data from single HBTs is achieved, and several circuits based on Gilbert multiplier are designed for the purposes of model validation and high-speed applications. Nonlinear properties of these circuits are measured and compared with the simulation results from different bipolar transistor models. The variable gain amplifier reported in this paper achieves the highest gain-bandwidth product of over 520 GHz under the limitation of measurement capability.

Over 500 GHz InP heterojunction bipolar transistors

Single heterojunction bipolar transistors (SHBTs) with cutoff frequencies as high as 520 GHz operating at current densities over 1400 kA/cm/sup 2/ have been demonstrated. We compare state-of-the-art HBT technologies, focusing on the aspects of scalability and speed, breakdown voltage, thermal properties, and the demands future applications will require from these high-performance devices.

Low-power high-speed operation of submicron InP-InGaAs SHBTs at 1 mA

Scaling of submicron InP-InGaAs HBTs is investigated for low-power high-speed applications in mixed signal circuits. Device performance for transistors fabricated with a 0.5-/spl mu/m emitter width and varying emitter lengths are studied. The 0.5 /spl mu/m/spl times/2 /spl mu/m devices yielded excellent low-current RF performance, with an f/sub T/=173 GHz and an f/sub MAX/=187 GHz at 1 mA, the highest values reported for InP-based devices to date.

Submicron scaling InP/InGaAs single heterojunction bipolar transistor technology with f/sub T/ > 400 GHz for >100 GHz applications

We describe a high-speed triple metal InP SHBT technology in this paper. With respect to scaling, we have measured f/sub T/ from 300 GHz to 450 GHz, and f/sub MAX/ from 200 GHz to 380 GHz. The proposed technology also features triple metal interconnections, MIM capacitors and NiCr thin film resistors. A CML static frequency divider is designed and simulated from DC to 122 GHz toggling rate at a power consumption of 141 mW.

Vertical scaling of type I InP HBT with FT > 500 GHZ

We have fabricated the high-speed InP/InGaAs-based single heterojunction bipolar transistors (SHBTs) with current gain cutoff frequency, fT from 166GHz to over 500GHz by the approach of vertical scaling. Collector thickness is reduced from 3000A to 750A and the peak current density is increased up to 1300kA/cm2. In this paper, device rf performance has been compared with respect to materials with different vertical dimensions. The scaling limitation is also studied by analytical approach. The extracted physical parameters suggest that the parasitic emitter resistance is the major limit on further enhancing ultra-scaled HBT intrinsic speed due to the associated RECBC delay. The cut-off frequency of a 500A collector SHBT has been measured and the results indicate a dramatic drop on fT, supporting the conclusion projected by model analysis. It is also commented that for deeply downscaled HBTs, impact ionization could be another degrading mechanism limits device bandwidth.

Vertical scaling of type I InP HBT with f/sub T/ > 500 GHz

We have fabricated the high-speed InP/InGaAs-based single heterojunction bipolar transistors (SHBTs) with current gain cutoff frequency, f/sub T/ from 166GHz to over 500GHz by the approach of vertical scaling. Collector thickness is reduced from 3000/spl Aring/ to 750/spl Aring/ and the peak current density is increased up to 1300kA/cm/sup 2/. In this paper, device RF performance has been compared with respect to materials with different vertical dimensions. The scaling limitation is also studied by analytical approach. The extracted physical parameters suggest that the parasitic emitter resistance is the major limit on further enhancing ultra-scaled HBT intrinsic speed due to the associated RECBC delay. The cut-off frequency of a 500/spl Aring/ collector SHBT has been measured and the results indicate a dramatic drop on f/sub T/, supporting the conclusion projected by model analysis. It is also commented that for deeply downscaled HBTs, impact ionization could be another degrading mechanism limits device bandwidth.