THz Device Design for SiGe HBT under Sub-room Temperature to Cryogenic Conditions

Gupta, Dinesh and Venkateswarlu, Sankatali and Badami, Oves and Nayak, Kaushik (2020) THz Device Design for SiGe HBT under Sub-room Temperature to Cryogenic Conditions. In: 5th IEEE International Conference on Emerging Electronics, ICEE 2020, 26 - 28 November 2020, New Delhi.

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BiCMOS technology can be a possible replacement for FDSOI and FinFET technology due to their higher transconductance, which allows them to operate at in THz range i.e. radio frequencies (RF) in addition to their higher voltage handling ability. The most advanced SiGe heterojunction bipolar transistor (HBT) technology (55-nm BiCMOS) demonstrates room temperature cut-off frequency ($f_{\mathrm{t}}$) and maximum oscillation frequency ($f_{\max}$) of 320 GHz and 370 GHz respectively. In this paper, we performed TCAD analysis to investigate the performance metrics, $f_{\mathrm{t}}$ and $f_{\max}$ of the SiGe HBT at different cryogenic temperatures. The calibrated Gummel characteristics reveals that a record DC current gain of $1.2\times 10^{4}$ is obtained at 77 K for $\mathrm{V}_{\text{BE}}=\mathrm{V}_{\text{CE}}=1.2\ \mathrm{V}$. The HBT device employs bandgap engineering by linearly varying the Ge concentration in the base region, which enhances the device performance. Both the bandgap engineering with linearly graded Germanium (Ge) profile (induces intrinsic drift field in the base) and the cryogenic operation of the HBT device results in enhancement of $f_{\mathrm{t}}$ and $f_{\max}$. Our simulations predict that the value of peak $f_{\mathrm{t}}$ decreases below 100 K due to increase in the emitter junction capacitance and the peak $f_{\max}$ increase is due to decrease in collector junction capacitance and base resistance. The aggregate metric $f_{\mathrm{t}}+f_{\max} > 1.2\ \text{THz}$ is achieved under cryogenic condition without scaling the device, this advantage can be utilized in the THz device applications. © 2020 IEEE.

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IITH Creators:
IITH CreatorsORCiD
Badami, Oves
Item Type: Conference or Workshop Item (Paper)
Additional Information: The authors would like to thank the Electron Devices Research Laboratory (EDR Lab) members of the department of Electrical Engineering, Indian Institute of Technology Hyderabad for their valuable discussions and feedback. This work was supported by Council of Scientific & Industrial Research (CSIR), India.
Uncontrolled Keywords: $f_{max}$; $f_{t}$; bandgap engineering; BiCMOS; Cryogenic temperature; current gain; Gummel-characteristics; HBT; SiGe; THz
Subjects: Electrical Engineering
Divisions: Department of Electrical Engineering
Depositing User: . LibTrainee 2021
Date Deposited: 24 Nov 2022 10:42
Last Modified: 24 Nov 2022 10:42
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