A spectroscopy setup has been developed for the characterization of semiconductor quantum structures and bulk materials. Photoluminescence (PL), Photoreflectance (PR), Electroreflectance (ER), Transmission (T%), Reflection (R%), Surface photovoltage (SPV) and Photothermal pyroelectric (PPE) spectroscopy measurements are performed routinely . The setup consists of 10 to 300K available (ARS CCR with Temp Control) 325nm, 532 nm, 808 nm and 632 nm lasers QTH and Xe arc lamp Oriel (1/8 m) and ScienceTech (1/4 m) monochromators EG&G 7260 Lock-in amplifier and chopper are performed routinely by using this facility.

Transport measurement laboratory consists of current-voltage (I-V), Capacitance-Voltage (C-V), Electrochemical Capacitance Voltage profiler (PN-4300, PN-4400 system), Deep level transient spectroscopy (DLTS) and Hall measurements, fabrication of electrical contact using Rapid Thermal Annealing (RTA) facilities. The measurements can be performed at large temperature range (40K-360K). Many materials system such as GaAs, GaP, InP, AlGaAs, InGaAs, AlInGaP, GaN, ZnO, and two dimensional electron gas system such as AlGaAs/GaAs, Laser and Detector structures have been studied using above systems.

For epitaxial layers, the information regarding the crystalline quality is extremely important where one measures a very small deviation from the lattice constant of substrate. For ternary and quaternary alloys, such information provides an estimate of the alloy composition which is further supported by the spectroscopic measurements. High resolution x-ray diffraction (HRXRD, PANalytical X’Pert MRD Pro) facility is routinely used for the structural characterization of MOVPE grown epitaxial layers, laser and detector structures.

• Atomic Force Microscope
• SEM/TEM with complete facility for cross section HRTEM
• Spectroscopic Ellipsometer
• Ultrafast spectroscopy (ns, ps, fs time scale)
• Raman Spectroscopy
• X-ray reflectivity and TXRF facility
• Several beam lines at Synchrotron Radiation facility

Device Processing Laboratory

Device processing laboratory includes a photolithography, contact deposition, rapid thermal annealing, scriber and plasma enhanced chemical vapor phase (PECVD) systems etc.

One of the important steps of processing of laser diodes is optical lithography, which defines the dimension of laser diodes.  A manual mask aligner (Quintel Q4000-6TL) has been used for this purpose. Stripe patterns of 30-150um width are routinely transferred onto GaAs wafers, and laser structures using, spin coater (Max ~10,000 RPM), chrome and iron oxide  masks and both positive and negative photoresists.

Another important step of laser diode fabrication is formation of Ohmic contacts to both p- and n-side of the diode. one class 1000 compatible vacuum coating unit (with both thermal and electron-beam facilities) with turbo molecular pump has been used for this purpose installed. Several materials such as Gold, Gold–Germanium, Titanium, Nickel, Platinum, etc. have been deposited on GaAs, and GaP based devices. Alloyed contact formation at metal–semiconductor junction without deleterious metal diffusion is achieved using isothermal rapid thermal annealing setup (Indigenously developed in RRCAT, typically it can reach 650⁰C in 25 sec).

Karl Suss scriber is used for cleaving semiconductor Laser and Detector devices. The 1-2mil wire bonder (High bond) is used for bonding semiconductor Laser and Detector devices.