Cryogenic Optoelectronic Characterization of InGaAsP LEDs for Low-Energy Detector Calibration

Abstract

We measured the emission spectra and current-voltage (IV) characteristics of commercial InGaAsP LEDs in a cryostat over a temperature range from 7 K to 300 K. At a constant operating current of 3.3 mA, the peak emission wavelength of the 1200 nm (1650 nm) LED decreased from 1202.3 +/- 0.5 nm (1665.5 +/- 0.6 nm) at 300 K to 1143.1 +/- 0.3 nm (1539.5 +/- 2.2 nm) at 7 K, demonstrating a strong temperature dependence. The cut-in voltage increased systematically with decreasing temperature, in agreement with conventional diode theory. To assess junction self-heating effects, we conducted pulsed IV measurements at different duty cycles. The extracted apparent series resistance showed a clear duty-cycle dependence, whereas the cut-in voltage remained unchanged within experimental uncertainty, indicating that self-heating primarily influenced the IV slope rather than the cut-in voltage. These results quantitatively characterize the thermal behavior of both the spectral peak and key electrical parameters, supporting the application of InGaAsP LEDs as cryogenic calibration light sources.

arXiv comment8 pages, 11 figures