Rapid and Minimally Invasive Quantum Cascade Wafer Testing

In this work, we demonstrate a rapid and minimally invasive technique for wafer quality testing, which requires using a single etch and metallization step to fabricate a single mesa. The mesa's electrical and optical properties are characterized and compared with those of a quantum cascade (QC) laser made from the same wafer, to test the validation of our method. This technique is ideal for determining key QC laser parameters and also the level of agreement between a design and actual laser performance without requiring laser processing which can be highly invasive, labor intensive, and time consuming. Measurements between these mesas and actual reference lasers made from the same wafer material differed by less than ~10% in parameters such as emission wavelength, full-width at half-maximum, turn-on voltage, and maximum operating current density, thus proving the adequacy of our technique.