Advanced SiGe:C HBTs at Cryogenic Temperatures and Their Compact Modeling With Temperature Scaling

Jin, Xiaodi; Müller, Markus; Sakalas, P.; Mukherjee, A.; Zhang, Yaxin; Schröter, M.

doi:10.1109/jxcdc.2021.3130041

Cited by 11 publications

(5 citation statements)

References 25 publications

(35 reference statements)

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“…For Φ BI (CV ), the error bars represent the 2-σ error in Φ BI , obtained by performing fits with (2) for 100 C BE − V BE sweeps with errors randomly determined based on a normal distribution defined by the uncertainty in the measured C BE . The extracted Φ BI (CV ) is observed to weakly increase with decreasing temperature, consistent with observations for similar devices [10] and Schottky diodes [17]. In contrast, Φ BI (IV ) exhibits a stronger dependence on temperature, as observed previously for Schottky diodes [11,17], and differs markedly in magnitude from the Φ BI (CV ).…”

Section: Resultssupporting

confidence: 88%

“…II, these data are analyzed to obtain Φ BI from the I C − V BE and C BE − V BE characteristics. At room temperature, Φ BI (CV ) is found to be 0.83 V, in good agreement with [10]. This value is specified as the room temperature value for Φ BI (IV ) to facilitate comparison at other temperatures.…”

Section: Resultssupporting

confidence: 56%

“…The cryogenic microwave performance of SiGe HBTs has been investigated following their initial development in the late 1980s [6] as various performance metrics such as transconductance and noise figure improve with cooling. However, below ∼ 77 K, these improvements are observed to plateau with decreasing temperature [7,8], corresponding to a temperaturedependent ideality factor n(T ) that greatly exceeds unity at cryogenic temperatures [9,10]. This behavior differs markedly from the predictions of thermionic emission theory of an ideal junction in which n is equal to unity and is independent of temperature, and the transconductance increases inversely with temperature.…”

Section: Introductionmentioning

confidence: 83%

“…Following standard procedure [10,11] C BE − V BE characteristics are obtained using a vector network analyzer (VNA, Keysight E5061B). In reverse-bias and low-forward bias regimes, the Y − parameters are given by Y 11 = g BE + jω(C BE + C BC ) and…”

Section: B Experimental Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Investigation of Cryogenic Current-Voltage Anomalies in SiGe HBTs: Role of Base-Emitter Junction Inhomogeneities

Naik¹,

Gabritchidze²,

Kooi³

et al. 2023

Preprint

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The anomalous current-voltage characteristics of cryogenic SiGe HBTs have been a topic of investigation for many years. Proposed explanations include quasiballistic transport of electrons across the base or tunneling from the emitter to the collector, but inconsistencies exist with these hypotheses. Although similar behavior occurs in Schottky junctions and has been attributed to lateral inhomogeneities in the junction potential, this explanation has not been considered for SiGe HBTs. Here, we experimentally investigate this hypothesis by characterizing the base-emitter builtin potential and its temperature dependence using both capacitance-voltage and current-voltage characteristics. We observe a marked discrepancy in the built-in potential obtained using these two methods at cryogenic temperatures, supporting the origin for the anomalous behavior of SiGe HBTs as arising from lateral inhomogeneities in the base-emitter junction potential. This work helps to identify the physical mechanisms limiting the cryogenic microwave noise performance of SiGe HBTs.

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Section: Resultssupporting

confidence: 88%

Section: Resultssupporting

confidence: 56%

Section: Introductionmentioning

confidence: 83%

Section: B Experimental Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of Cryogenic Current-Voltage Anomalies in SiGe HBTs: Role of Base-Emitter Junction Inhomogeneities

Naik¹,

Gabritchidze²,

Kooi³

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…The small-signal circuit parameters are calibrated using the extracted and measured device characteristics given in [7] and [19] in order to examine the behavior of the LNA at CT. In essence, we found the scale factors of the parameters when the operating temperature decreased from 300 to 4 K RT to CT. We then adjusted the room temperature small-signal parameters by applying these scale factors while taking the transistor sizes into consideration, and the altered circuit parameters are presented in Table II.…”

mentioning

confidence: 99%

A 0.32×0.12 mm² Cryogenic BiCMOS 0.1–8.8 GHz Low Noise Amplifier Achieving 4 K Noise Temperature for SNWD Readout

Peng,

Benserhir,

Castaneda

et al. 2024

IEEE Trans. Microwave Theory Techn.

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A significant number of cryogenic low-noise amplifiers (cryo-LNAs) are required for the readout of superconducting nanowire detector (SNWD) arrays. It is desirable to have compact cryo-LNAs in place so that the size of the readout circuitry for the SNWD array can be reduced. In this study, we first examined the bandwidth, linearity, and noise requirements of the cryo-LNA for SNWD readout. After that, the design and implementation of a wideband silicongermanium (SiGe) BiCMOS cryo-LNA were described in detail. The LNA features two cascode stages with resistive shuntshunt feedback for wideband input impedance matching. The capacitive peaking techniques and emitter inductive degeneration via a slab inductor were utilized to increase the bandwidth without compromising the layout's compactness. To ensure the amplifier works well at cryogenic temperatures, we modified the model parameters from the foundry-provided models based on the device's reported cryogenic test data. The measurement results at 3.6 K demonstrate that the cryo-LNA, occupying a core size of only 0.03 mm 2 , achieves a noiseequivalent temperature (NET) of 4-10 K and an average gain of 30.5 dB in the frequency band from 0.1 to 8.8 GHz, under a power consumption of 8.2 mW. We successfully integrated this LNA with a quantum sensor array on a printed circuit board (PCB) and obtained favorable test results, demonstrating the potential application of LNAs for reading large-scale SNWDs.

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Investigation of cryogenic current–voltage anomalies in SiGe HBTs: Role of base–emitter junction inhomogeneities

Naik,

Gabritchidze,

Chen

et al. 2024

Journal of Applied Physics

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The deviations of cryogenic collector current–voltage characteristics of SiGe heterojunction bipolar transistors (HBTs) from ideal drift-diffusion theory have been a topic of investigation for many years. Recent work indicates that direct tunneling across the base contributes to the non-ideal current in highly scaled devices. However, cryogenic discrepancies have been observed even in older-generation devices for which direct tunneling is negligible, suggesting that another mechanism may also contribute. Although similar non-ideal current–voltage characteristics have been observed in Schottky junctions and were attributed to a spatially inhomogeneous junction potential, this explanation has not been considered for SiGe HBTs. Here, we experimentally investigate this hypothesis by characterizing the collector current ideality factor and built-in potential of a SiGe HBT vs temperature using a cryogenic probe station. The temperature dependence of the ideality factor and the relation between the built-in potential as measured by capacitance–voltage and current–voltage characteristics are in good qualitative agreement with the predictions of a theory of electrical transport across a spatially inhomogeneous junction. These observations suggest that inhomogeneities in the base–emitter junction potential may contribute to the cryogenic non-idealities. This work helps to identify the physical mechanisms limiting the cryogenic microwave noise performance of SiGe HBTs.

show abstract

Advanced SiGe:C HBTs at Cryogenic Temperatures and Their Compact Modeling With Temperature Scaling

Cited by 11 publications

References 25 publications

Investigation of Cryogenic Current-Voltage Anomalies in SiGe HBTs: Role of Base-Emitter Junction Inhomogeneities

Investigation of Cryogenic Current-Voltage Anomalies in SiGe HBTs: Role of Base-Emitter Junction Inhomogeneities

A 0.32×0.12 mm² Cryogenic BiCMOS 0.1–8.8 GHz Low Noise Amplifier Achieving 4 K Noise Temperature for SNWD Readout

Investigation of cryogenic current–voltage anomalies in SiGe HBTs: Role of base–emitter junction inhomogeneities

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Advanced SiGe:C HBTs at Cryogenic Temperatures and Their Compact Modeling With Temperature Scaling

Cited by 11 publications

References 25 publications

Investigation of Cryogenic Current-Voltage Anomalies in SiGe HBTs: Role of Base-Emitter Junction Inhomogeneities

Investigation of Cryogenic Current-Voltage Anomalies in SiGe HBTs: Role of Base-Emitter Junction Inhomogeneities

A 0.32×0.12 mm2 Cryogenic BiCMOS 0.1–8.8 GHz Low Noise Amplifier Achieving 4 K Noise Temperature for SNWD Readout

Investigation of cryogenic current–voltage anomalies in SiGe HBTs: Role of base–emitter junction inhomogeneities

Contact Info

Product

Resources

About

A 0.32×0.12 mm² Cryogenic BiCMOS 0.1–8.8 GHz Low Noise Amplifier Achieving 4 K Noise Temperature for SNWD Readout