In Situ Substrate Temperature Measurement During MBE by Band-Edge Reflection Spectroscopy

Abstract

The use of band-edge reflection spectroscopy (BRS) to determine the substrate temperature during MBE is reviewed. Data are presented for Si, GaAs, InP and CdZnTe substrates, and the use of BRS during the growth of ZnTe on Si is demonstrated. We discuss complications that arise due to optical interference in the epitaxial layers, and methods to compensate for the effects of interference are described.

Desorption behavior of antimony multilayer passivation on GaAs (001)

“…The samples were heated at 10°C/min with interruptions of on the order of 1 min at key temperatures where RHEED and/or reflectance data were collected. The reflectance data were obtained using a commercial instrument which utilizes the shift in absorption band edge as a function of temperature characteristic of a semiconductor 16 to calibrate the temperature of the substrate once the Sb multilayer had desorbed. We have found that the actual sample temperature and that measured by the thermocouple agree to within 7°C.…”

A UNION OF THE REAL-SPACE AND RECIPROCAL-SPACE VIEW OF THE GaAs(001) SURFACE

“…Another implementation of in situ band gap determination, is to bring white light in the pyrometer port and measure the band-edge reflection spectroscopy using the backreflected light coming out of the pyrometer viewport. 32 This method works well for bare substrates but suffers from optical interference effects, especially when the films are smooth and uniform in thickness (precisely what one wants to achieve with MBE).…”

Advances in HgCdTe-based infrared detector materials: the role of molecular-beam epitaxy

“…The substrate temperature sensor relies on the method of absorption-edge spectroscopy, 15,18 conducted in reflection mode, to sense the bandgap, and hence temperature, of a 2 cm x 2 cm Si "witness" wafer that is conductively mounted on the back side of the substrate mounting block. 9,16 This measurement technique requires optical access to the backside of the substrate mounting block, which is provided in our MBE systems via a linear quartz light pipe installed on a single-axis manipulator.…”

“…Sensors developed for HgCdTe alloy composition, [9][10][11][12]14 substrate temperature, 15 and source fluxes 16 enable the growth process to be monitored and, in many cases, controlled using closed-loop feedback control paradigms. This approach can substantially increase the yield of grown layers that meet target specifications for optical properties and crystallographic defects and dramatically shorten the time required for establishment and qualification of new growth processes.…”