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The impact of the temperature on In0.53Ga0.47As nTFETs

Influence de la température sur les nTFETs In0.53Ga0.47As


C. Bordallo
University of São Paulo - Brazil

J. A. Martino
University of São Paulo - Brazil

P. G. D. Agopian
University of São Paulo - Brazil

A. Alian
imec - Belgium

Y. Mols
imec - Belgium

R. Rooyackers
imec - Belgium

A. Vandooren
imec - Belgium

A. Verhulst
imec - Belgium

D. Mocuta
imec - Belgium

D. Lin
imec - Belgium

E. Simoen
imec - Belgium

C. Claeys
KU Leuven - Belgium

N. Collaert
imec - Belgium



Published on 16 February 2018   DOI : 10.21494/ISTE.OP.2018.0224

Abstract

Résumé

Keywords

Mots-clés

In this paper, a comparative study between the use of spin on glass and gas phase Zn diffusion of the p++ source of InGaAs TFETs was performed. The use of Zn gas phase doping at the source reduces the tunneling length which results in an enhancement of ION, higher transistor efficiency and intrinsic voltage gain at lower voltages. The main parameters of gas-phased-diffused In0.53Ga0.47As nTFETs with gate stacks composed by 3 nm or 2 nm HfO2 on top of 1 nm Al2O3 have been analyzed. The resulting equivalent oxide thickness (EOT) was about 0.8 nm and 1.0 nm, respectively. The lower EOT improves the electrostatic coupling, resulting in a lower SS (sub 60 mV/dec at room temperature) leading to a higher gm/IDS in weak conduction. TCAD simulations have shown that the ambipolar effect is significant for higher VDS, degrading SS and consequently gm/IDS in the weak conduction regime, also shifting the gm/IDS peak to higher VGS direction due to the increase of IOFF. The AV peak is strongly degraded by an increase of the temperature due to the increase of the trap-assisted-tunneling (TAT) and Shockley-Read-Hall (SRH) generation mechanisms. For higher VGS the AV is lower, and at the same time less sensitive to temperature variations, which is a favorable regime for temperature-dependent analog operation.

In this paper, a comparative study between the use of spin on glass and gas phase Zn diffusion of the p++ source of InGaAs TFETs was performed. The use of Zn gas phase doping at the source reduces the tunneling length which results in an enhancement of ION, higher transistor efficiency and intrinsic voltage gain at lower voltages. The main parameters of gas-phased-diffused In0.53Ga0.47As nTFETs with gate stacks composed by 3 nm or 2 nm HfO2 on top of 1 nm Al2O3 have been analyzed. The resulting equivalent oxide thickness (EOT) was about 0.8 nm and 1.0 nm, respectively. The lower EOT improves the electrostatic coupling, resulting in a lower SS (sub 60 mV/dec at room temperature) leading to a higher gm/IDS in weak conduction. TCAD simulations have shown that the ambipolar effect is significant for higher VDS, degrading SS and consequently gm/IDS in the weak conduction regime, also shifting the gm/IDS peak to higher VGS direction due to the increase of IOFF. The AV peak is strongly degraded by an increase of the temperature due to the increase of the trap-assisted-tunneling (TAT) and Shockley-Read-Hall (SRH) generation mechanisms. For higher VGS the AV is lower, and at the same time less sensitive to temperature variations, which is a favorable regime for temperature-dependent analog operation.

TFET Temperature Analog parameters Current conduction mechanisms intrinsic voltage gain sub-60mV/dec.

TFET Temperature Analog parameters Current conduction mechanisms intrinsic voltage gain sub-60mV/dec.