| AVS 58th Annual International Symposium and Exhibition | |
| Spectroscopic Ellipsometry Focus Topic | Thursday Sessions |
| Session EL-ThP |
| Session: | Spectroscopic Ellipsometry Poster Session |
| Presenter: | JaeJin Yoon, Kyung Hee University, Republic of Korea |
| Authors: | J.J. Yoon, Kyung Hee University, Republic of Korea T.J. Kim, Kyung Hee University, Republic of Korea S.Y. Hwang, Kyung Hee University, Republic of Korea M.S. Diware, Kyung Hee University, Republic of Korea Y.D. Kim, Kyung Hee University, Republic of Korea Y.C. Chang, Academia Sinica, Taiwan, Republic of China |
| Correspondent: | Click to Email |
InSb is a promising material for optical devices, particularly for high-frequency and nonlinear-optical applications. InSb has a high electron mobility and offer excellent design flexibility as a result of its large conduction-band offset in multilayer structures. Consequently, InSb offers significant potential for devices such as quantum-well lasers, laser diodes, and heterojunction bipolar transistors. A knowledge of the dielectric function at various temperatures is required for optimizing the properties for specific device applications. In-situ control of growth is also becoming an important technique. Therefore, the dielectric function at growth temperatures is also needed. On the other hand, critical point (CP) energies can be better identified from low-temperature data, where the decreased electron-phonon interaction allows separation of CP structures that are nearly degenerate at room temperature.
Although the optical properties of InSb have been well studied, there are only a few reports of their temperature dependence in the 1.2 to 5.6 eV spectral ranges [1]. Here, we report results of an investigation of the temperature dependence of the dielectric response of InSb from 22 K to 700 K and from 0.74 to 6.57 eV.
Spectroscopic ellipsometric (SE) data were obtained on a bulk semi-insulating InSb (100) substrate. The cryostat consisted of a stainless-steel chamber with high-quality stress-free fused-quartz windows. To avoid condensation at low temperatures, the sample was maintained in ultrahigh vacuum during measurement. SE data were obtained at an angle of incidence of 70.41° using a conventional rotating-compensator system with a diode-array detector. The influence of the oxide overlayer was removed mathematically by a multilayer calculation. In the E2 energy region only four structures are clearly resolved at 300 K. However, at 22 K the E2' and E2 structures are seen to consist of five CPs. We identified the origin of these structures with band-structure calculations using the LASTO method. Separation of the E0', E0'+Δ0', E2, E2+Δ2, E2', E1' and E1'+Δ1' CPs was clearly found in the region of the E2 peak. Two saddle-point transitions, Δ5cu-Δ5vu and Δ5cl-Δ5vu, are clearly seen. We also determined the temperature dependences of the newly observed transitions near 5.9 eV. These results will be useful in a number of contexts, including the design of optoelectronic devices based on InSb, as data for improved band structure calculations, and for in-situ monitoring.
[1] S. Logothetidis, L. Vina and M. Cardona, Phys. Rev. B 31, 947 (1985).