Lateral carrier diffusion and current gain in terahertz InGaAs/InP double-heterojunction bipolar transistors

Chiang, Han-Wei; Rode, Johann C.; Choudhary, Prateek; Rodwell, M.J.W.

doi:10.1063/1.4862405

Cited by 7 publications

(14 citation statements)

References 17 publications

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“…1 However, when the device is scaled, the DC current gain (b ¼ I C /I B ) decreases. 3,4 As shown in Fig. 1, experimental devices with base-emitter junction widths (W E ) of 200 and 75 nm exhibit b of approximately 20 and 8, respectively.…”

Section: Introductionmentioning

confidence: 95%

“…I B,Bulk arises from recombination mechanisms in the bulk base semiconductor and is dominated in THz HBTs by Auger recombination due to the high doping concentration. 3 In THz HBTs, I B,Bulk is proportional to the emitter current and hence at a fixed current density scales in proportion to the base-emitter junction area,…”

Section: Introductionmentioning

confidence: 99%

“…I B,Edge originates from surface recombination and from lateral diffusion of the injected electrons to the base contact via the bulk base region and through the surface depletion layer of the base semiconductor induced by surface defect states. [3][4][5] Since this current emanates from the edge of the base-emitter junction, it scales in proportional to the junction periphery, P je ¼ 2(W E þ L E ). The DC current gain in HBTs can be written as…”

Section: Introductionmentioning

confidence: 99%

“…If the base doping concentration is increased, the Auger recombination lifetime decreases, and hence s n and b Bulk decrease. 3,6 In a DHBT with a narrow emitter, b is also limited by the edge current, and b decreases as W E reduces. 3,4 We have previously modelled DC current gain using a commercial transport simulator.…”

Section: Introductionmentioning

confidence: 99%

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Optimization of direct current performance in terahertz InGaAs/InP double-heterojunction bipolar transistors

Chiang

Rode

Choudhary

et al. 2014

Journal of Applied Physics

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As the dimensions of In0.53Ga0.47As/InP double-heterojunction bipolar transistors (DHBTs) scale for terahertz applications, the DC current (β) decreases. To improve the DC performance in such scaled devices, we analyze three modified HBT geometries: a HBT with a surface pulse-doped layer in the base, a HBT having this pulse-doped layer under the emitter junction and under the base contact, but with it removed by etching in the region between the base and emitter contacts, and a device, necessarily fabricated by regrowth, in which the pulsed doped layer is present under only the base contacts. Based on a drift-diffusion/recombination model, carrier transport in the DHBT base is simulated and the corresponding β is computed using TCAD software. The structures with a pulse doped layer can attain β = 31 ∼ 39 at 100 nm emitter width. The structures with a trench between the base contact and emitter show β = 39 ∼ 54 at 100 nm emitter width. Finally, the structure with recessed base-emitter junction and regrown emitter demonstrate β = 62–119 at 100 nm emitter width.

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Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Optimization of direct current performance in terahertz InGaAs/InP double-heterojunction bipolar transistors

Chiang

Rode

Choudhary

et al. 2014

Journal of Applied Physics

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“…Contamination from resist chemistry or prior process steps can increase ρ c ; contamination must be avoided or removed, or the contaminated surface penetrated by the contact metal. Yet, because the base doping near the upper surface is high to enable low ρ c [6], but decreases sharply with depth to reduce Auger recombination hence increase β [11], the contacts must not penetrate more than a few nanometers. The contacts must not degrade or deeply interdiffuse into the base during operation at high current densities or at elevated temperatures.…”

Section: Mesa Hbt Base-collector Parasiticsmentioning

confidence: 99%

Indium Phosphide Heterobipolar Transistor Technology Beyond 1-THz Bandwidth

Rode¹,

Chiang²,

Choudhary³

et al. 2015

IEEE Trans. Electron Devices

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Recent improvements in the fabrication technology of InGaAs/InP heterobipolar transistors have enabled highly scaled transistors with power gain bandwidths above 1 THz. Limitations of the conventional fabrication process that reduce RF bandwidth have been identified and mitigated, among which are high resistivity base ohmic contacts, resistive base electrodes, excessive emitter end undercut, and insufficient undercut of largediameter base posts. A novel two-step deposition process for self-aligned metallization of sub-20-nm bases has been developed and demonstrated. In the first step, a metal stack is directly evaporated onto the base semiconductor without any lithographic processing so as to minimize contamination from resist/developer chemistry. The composite metal stack exploits an ultrathin layer of platinum that controllably reacts with base, yielding low contact resistance, as well as a thick refractory diffusion barrier, which permits stable operation at high current densities and elevated temperatures. Further reduction of overall base access resistance is achieved by passivating base and emitter semiconductor surfaces in a combined atomic layer deposition Al 2 O 3 and plasma-enchanced chemical vapor depositon SiN x sidewall process. This technology enables the deposition of low-sheetresistivity base electrodes, further improving overall base access resistance and f max bandwidth. Additional process enhancements include the significant reduction of device parasitics by scaling base posts and controlling emitter end and base postundercut.

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Multi-dimensional optimization of In0.53Ga0.47As thermophotovoltaic cell using real coded genetic algorithm

Gamel

Ker

Lee

et al. 2021

Sci Rep

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The optimization of thermophotovoltaic (TPV) cell efficiency is essential since it leads to a significant increase in the output power. Typically, the optimization of In0.53Ga0.47As TPV cell has been limited to single variable such as the emitter thickness, while the effects of the variation in other design variables are assumed to be negligible. The reported efficiencies of In0.53Ga0.47As TPV cell mostly remain < 15%. Therefore, this work develops a multi-variable or multi-dimensional optimization of In0.53Ga0.47As TPV cell using the real coded genetic algorithm (RCGA) at various radiation temperatures. RCGA was developed using Visual Basic and it was hybridized with Silvaco TCAD for the electrical characteristics simulation. Under radiation temperatures from 800 to 2000 K, the optimized In0.53Ga0.47As TPV cell efficiency increases by an average percentage of 11.86% (from 8.5 to 20.35%) as compared to the non-optimized structure. It was found that the incorporation of a thicker base layer with the back-barrier layers enhances the separation of charge carriers and increases the collection of photo-generated carriers near the band-edge, producing an optimum output power of 0.55 W/cm2 (cell efficiency of 22.06%, without antireflection coating) at 1400 K radiation spectrum. The results of this work demonstrate the great potential to generate electricity sustainably from industrial waste heat and the multi-dimensional optimization methodology can be adopted to optimize semiconductor devices, such as solar cell, TPV cell and photodetectors.

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Lateral carrier diffusion and current gain in terahertz InGaAs/InP double-heterojunction bipolar transistors

Cited by 7 publications

References 17 publications

Optimization of direct current performance in terahertz InGaAs/InP double-heterojunction bipolar transistors

Optimization of direct current performance in terahertz InGaAs/InP double-heterojunction bipolar transistors

Indium Phosphide Heterobipolar Transistor Technology Beyond 1-THz Bandwidth

Multi-dimensional optimization of In0.53Ga0.47As thermophotovoltaic cell using real coded genetic algorithm

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