Variable-wavelength frequency-domain terahertz ellipsometry

被引：73

作者：

Hofmann, T. ^{[1
,2
]}

Herzinger, C. M. ^{[3
]}

Boosalis, A. ^{[1
,2
]}

Tiwald, T. E. ^{[3
]}

Woollam, J. A. ^{[3
]}

Schubert, M. ^{[1
,2
]}

机构：

[1] Univ Nebraska, Dept Elect Engn, Lincoln, NE 68588 USA

[2] Univ Nebraska, Nebraska Ctr Mat & Nanosci, Lincoln, NE 68588 USA

[3] JA Woollam Co Inc, Lincoln, NE 68508 USA

来源：

REVIEW OF SCIENTIFIC INSTRUMENTS | 2010年 / 81卷 / 02期

基金：

美国国家科学基金会;

关键词：

backward wave oscillators; ellipsometry; optical polarisers; phosphorus; silicon; OPTICAL-CONSTANTS; TIME; SPECTROSCOPY; MULTISAMPLE; CALIBRATION; SILICON;

D O I：

10.1063/1.3297902

中图分类号：

TH7 [仪器、仪表];

学科分类号：

0804 ; 080401 ; 081102 ;

摘要：

We report an experimental setup for wavelength-tunable frequency-domain ellipsometric measurements in the terahertz spectral range from 0.2 to 1.5 THz employing a desktop-based backward wave oscillator source. The instrument allows for variable angles of incidence between 30 degrees and 90 degrees and operates in a polarizer-sample-rotating analyzer scheme. The backward wave oscillator source has a tunable base frequency of 107-177 GHz and is augmented with a set of Schottky diode frequency multipliers in order to extend the spectral range to 1.5 THz. We use an odd-bounce image rotation system in combination with a wire grid polarizer to prepare the input polarization state. A highly phosphorous-doped Si substrate serves as a first sample model system. We show that the ellipsometric data obtained with our novel terahertz ellipsometer can be well described within the classical Drude model, which at the same time is in perfect agreement with midinfrared ellipsometry data obtained from the same sample for comparison. The analysis of the terahertz ellipsometric data of a low phosphorous-doped n-type Si substrate demonstrates that ellipsometry in the terahertz spectral range allows the determination of free charge-carrier properties for electron concentrations as low as 8x10(14) cm(-3).

引用

页数：7

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