Photoluminescence from room-temperature bulk germanium

Germanium is a vital semiconductor material due to its ability to facilitate electron transition between the valence and conduction bands. Measuring the band gap of germanium, which determines its utility in semiconductor applications, involves using Photoluminescent (PL) Spectroscopy. This presentation shows different PL measurements of n-type, p-type, and intrinsic germanium samples at room temperature. Two sets of measurements were taken, one set using a 1550nm laser and another using a 980nm laser, both sets of data used a cooled  InGaAs detector. The indirect and direct band gaps, observed from the PL, show the photonic emissions as electrons transition from the conduction band to the valence band. These transitions represent the electronic transitions in germanium, as well as the indirect and direct band gap energies. 

These experimental data on a normalized, intensity vs. wavelength graph demonstrate the different properties of the n-type, p-type, and intrinsic germanium samples. Germanium is typically used for devices such as transistors, infrared detectors, optical components for fiber optic systems, and laser diodes for silicon photonics. Understanding the bandgap and luminescence properties allows for better optimization of germanium-based semiconductor materials in advanced electronics and communication technologies. The ability to characterize these transitions with high precision enhances the use of germanium in developing efficient semiconductor devices.