An investigation of group iv alloys and their applications in bipolar transistors
An investigation of group iv alloys and their applications in bipolar transistors
A background doping concentration (1020cm-3) of C has been introduced into the base of SiGe HBTs with the aim of studying the effects of C on TED of B from the base. An electrical method is used to extract the bandgap narrowing in the base of SiGe and SiGe:C HBTs through measurements of the temperature dependence of Ic at different C/B reverse biases. The method is very sensitive to small amounts of dopant out-diffusion from the base and hence is ideal for determining the effect of C on TED. Extracted BGN values of 11meV and 173meV were obtained for the SiGe and SiGe:C HBTs respectively, for a C/B reverse bias of 0V. Increasing the C/B reverse bias to IV increased the extracted BGN of the SiGe HBT to 145meV, but left the SiGe:C value unchanged. This demonstrates that no parasitic energy barrier exists in the SiGe:C HBT and that TED has been suppressed.
The effect of carbon position and concentration has been studied by introducing a peak C concentration of 1020cm -3 in the collector and 1.1 x 1019cm -3 or 1.5 x 1019cm -3 C in the base. From these measurements it has been shown that TED is only suppressed in the device with 1.5 x 1019cm -3 is needed to suppress TED and that the C needs to be co-located with the B profile.
The effects of carbon on the electrical properties of polycrystalline Si and SiGe films have been investigated. The resistivity, Hall mobility (μH) and effective carrier concentration (NEFF) of n- and p-type polySi1-yCy and polySi0.82-yGe0.18Cy layers have been measured for carbon contents between 0% and 8%. For the n-type polySi1-yCy and polySi0.82-yGe0.18Cy layers, the addition of small amounts of C (≤ 0.9%) was found to severely increase the resistivity of the layers, caused by a drop in NEFF AND μH. In contrast, for the p-type polySi1-yCy and polySi0.82-yGe0.18Cy layers, the effect of C on the resistivity was much less dramatic for C concentrations up to 7.8%. Measurements of the grain boundary energy barriers for the n-type polySi1-yCy and polySi0.82-yGe0.18Cy layers, extracted from the temperature dependence of the resistivity, showed that there was a square law dependence on carbon content.
University of Southampton
Anteney, Iain M
94c76a9c-ae7b-4297-a815-06f3cfd2e20f
2000
Anteney, Iain M
94c76a9c-ae7b-4297-a815-06f3cfd2e20f
Anteney, Iain M
(2000)
An investigation of group iv alloys and their applications in bipolar transistors.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
A background doping concentration (1020cm-3) of C has been introduced into the base of SiGe HBTs with the aim of studying the effects of C on TED of B from the base. An electrical method is used to extract the bandgap narrowing in the base of SiGe and SiGe:C HBTs through measurements of the temperature dependence of Ic at different C/B reverse biases. The method is very sensitive to small amounts of dopant out-diffusion from the base and hence is ideal for determining the effect of C on TED. Extracted BGN values of 11meV and 173meV were obtained for the SiGe and SiGe:C HBTs respectively, for a C/B reverse bias of 0V. Increasing the C/B reverse bias to IV increased the extracted BGN of the SiGe HBT to 145meV, but left the SiGe:C value unchanged. This demonstrates that no parasitic energy barrier exists in the SiGe:C HBT and that TED has been suppressed.
The effect of carbon position and concentration has been studied by introducing a peak C concentration of 1020cm -3 in the collector and 1.1 x 1019cm -3 or 1.5 x 1019cm -3 C in the base. From these measurements it has been shown that TED is only suppressed in the device with 1.5 x 1019cm -3 is needed to suppress TED and that the C needs to be co-located with the B profile.
The effects of carbon on the electrical properties of polycrystalline Si and SiGe films have been investigated. The resistivity, Hall mobility (μH) and effective carrier concentration (NEFF) of n- and p-type polySi1-yCy and polySi0.82-yGe0.18Cy layers have been measured for carbon contents between 0% and 8%. For the n-type polySi1-yCy and polySi0.82-yGe0.18Cy layers, the addition of small amounts of C (≤ 0.9%) was found to severely increase the resistivity of the layers, caused by a drop in NEFF AND μH. In contrast, for the p-type polySi1-yCy and polySi0.82-yGe0.18Cy layers, the effect of C on the resistivity was much less dramatic for C concentrations up to 7.8%. Measurements of the grain boundary energy barriers for the n-type polySi1-yCy and polySi0.82-yGe0.18Cy layers, extracted from the temperature dependence of the resistivity, showed that there was a square law dependence on carbon content.
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Published date: 2000
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Local EPrints ID: 464214
URI: http://eprints.soton.ac.uk/id/eprint/464214
PURE UUID: 19021c98-58f4-4ea8-8ad5-8fd696414803
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Date deposited: 04 Jul 2022 21:35
Last modified: 16 Mar 2024 19:20
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Author:
Iain M Anteney
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