Effects of Space Charges in IMPATT
Source at Terahertz Regime
Girish Chandra Ghivela and Joydeep Sengupta
Abstract Impact ionization and avalanche transit time (IMPATT) operation is based
on impact ionization and avalanche multiplication of charge carriers. However, its
operation is affected by the extra charges created in the space charge region. The
effect due to generation of extra charges is called as space charge effect. The space
charge effect in IMPATT can be numerically analyzed in the form of disturbance in
the actual electric field profile. In this chapter, authors have studied the space charge
effects in the double drift region (DDR) IMPATT based on Si, Ge, and GaAs at
frequency of 1–30 THz. Disturbances in the electric field profile, and drift voltages
have been analyzed here with analysis of resistances offered due to space charge
effects. This study will be helpful for optimum design of IMPATT diode at THz
against space charge effects.
Keywords Avalanche · Drift · Space charge effect · THz · Semiconductors
1 Introduction
Impact ionization avalanche transit time (IMPATT) diode is used to generate the
high power at microwave, millimeter wave, and sub-millimeter wave regions [1–4].
It has high power capability compared to other diodes [5, 6]. IMPATT operation is
based on impact ionization and avalanche multiplication of charge carriers. However,
its operation is affected by the extra charges created in the space charge region. The
effect due to generation of extra charges is called as space charge effect. Space charge
effect of IMPATT diode reduces the efficiency of the devices [7–10]. The effects
have been studied here by taking the one-dimensional double drift region (DDR)
IMPATT diode as shown in Fig. 1 [11–16]. The space charge effect in IMPATT can
be numerically analyzed in the form of disturbance in the actual electric field profile.
In this chapter, authors have studied the space charge effects in the DDR IMPATT
based on Si, Ge, and GaAs at frequency of 1–30 THz. Disturbances in the electric
G. Chandra Ghivela (B) · J. Sengupta
ECE Department, VNIT, Nagpur 440010, India
e-mail: girishvnit2012@gmail.com
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
A. Biswas et al. (eds.), Emerging Trends in Terahertz Engineering and System
Technologies, https://doi.org/10.1007/978-981-15-9766-4_2
23
Source at Terahertz Regime
Girish Chandra Ghivela and Joydeep Sengupta
Abstract Impact ionization and avalanche transit time (IMPATT) operation is based
on impact ionization and avalanche multiplication of charge carriers. However, its
operation is affected by the extra charges created in the space charge region. The
effect due to generation of extra charges is called as space charge effect. The space
charge effect in IMPATT can be numerically analyzed in the form of disturbance in
the actual electric field profile. In this chapter, authors have studied the space charge
effects in the double drift region (DDR) IMPATT based on Si, Ge, and GaAs at
frequency of 1–30 THz. Disturbances in the electric field profile, and drift voltages
have been analyzed here with analysis of resistances offered due to space charge
effects. This study will be helpful for optimum design of IMPATT diode at THz
against space charge effects.
Keywords Avalanche · Drift · Space charge effect · THz · Semiconductors
1 Introduction
Impact ionization avalanche transit time (IMPATT) diode is used to generate the
high power at microwave, millimeter wave, and sub-millimeter wave regions [1–4].
It has high power capability compared to other diodes [5, 6]. IMPATT operation is
based on impact ionization and avalanche multiplication of charge carriers. However,
its operation is affected by the extra charges created in the space charge region. The
effect due to generation of extra charges is called as space charge effect. Space charge
effect of IMPATT diode reduces the efficiency of the devices [7–10]. The effects
have been studied here by taking the one-dimensional double drift region (DDR)
IMPATT diode as shown in Fig. 1 [11–16]. The space charge effect in IMPATT can
be numerically analyzed in the form of disturbance in the actual electric field profile.
In this chapter, authors have studied the space charge effects in the DDR IMPATT
based on Si, Ge, and GaAs at frequency of 1–30 THz. Disturbances in the electric
G. Chandra Ghivela (B) · J. Sengupta
ECE Department, VNIT, Nagpur 440010, India
e-mail: girishvnit2012@gmail.com
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
A. Biswas et al. (eds.), Emerging Trends in Terahertz Engineering and System
Technologies, https://doi.org/10.1007/978-981-15-9766-4_2
23