Near-infrared transmission measurements on InGaAsP/InP LED wafers

The wavelength reproducibility of the LPE growth of InGaAsP/InP LED wafers has been investigated by near‐infrared transmission spectroscopy. The band gap wavelengths determined from the transmission measurements were shorter than the peak emission wavelengths of the LEDs prepared from the same wafer. The current heating effect was eliminated by determination of the peak emission wavelength as a function of driving current. The extrapolated peak emission wavelength at zero current showed good agreement with the band gap wavelength determined from the infrared transmission measurements. The run‐to‐run reproducibility of the LPE growth of 1215 nm LEDs was better than 5 nm at the central area of the wafers. The lateral homogeneity of the wafers was also determined by infrared transmission mapping. A relatively large wavelength shift was found near the edge of the wafers.