Light Probes Wafers Nondestructively
Sep 2008PicoQuant GmbHRequest Info
• decay down to 10 ps
• laser or LED excitation source
• wafers up to 10 cm
PicoQuant GmbH has a new version of its WaferCheck 150 that characterizes semiconductor materials for research and production purposes. It uses a nondestructive noncontact light probe to measure the time response of optoelectronic devices and performs quality checks on semiconductor processes and products, including photodetectors, GaAs/GaN wafers and solar cells, laser diodes and bright LEDs.
The instrument uses time-resolved photoluminescence to measure the electron-hole recombination rate of the semiconductor material. It works on raw materials, devices and structures. Pulsed light excites the electrons, and a photomultiplier tube (PMT) or multichannel plate (MCP) PMT detector measures the decay characteristics of the resulting fluorescence by time-correlated single-photon counting. The PMT detects decay times down to 60 ps, while the MCP-PMT detects down to 10 ps. An integrated laser power meter provides real-time control of the excitation level, and high-quality filters select the appropriate part of the emission spectrum. The light source is a laser diode head emitting 60- to 500-ps pulses at 375 to 485 nm, at 532 nm, or at 635 to 800 nm, with a repetition rate of up to 40 MHz, or pulsed LEDs emitting 0.5- to 1-ns pulses at 260 to 600 nm. A NanoHarp 250 or PicoHarp 300 data acquisition board logs the results, and FluoFit data analysis software computes exponential decay, lifetime distribution and anisotropy.
The standard instrument measures 300 × 375 × 150 mm and takes wafers up to 10 cm in size, but other sizes are available on request. The software is compatible with Microsoft Windows 2000 and XP.