Development of 100 mm AlN Single‐Crystal Growth and Subsequent Substrate Preparation

Aluminum nitride (AlN) is an ultrawide bandgap (UWBG) semiconductor with a proven record on meeting the needs for the ultraviolet (UV) devices operating in the range of 210–280 nm. 2‐inch AlN substrates are commercially available. These substrates demonstrate excellent crystalline quality, low absorption coefficient, and can be produced in capacities of multiple of thousands. The great potential of the AlN as a UWBG semiconductor is based on numerous theoretical predictions. However, substrates with diameter of 100 mm are needed to evaluate the potential and ensure practical commercialization. Here, we report on our approach to develop the 100 mm AlN single‐crystal substrates. The AlN single crystals are grown using physical vapor transport (PVT) technique. The crystals are sliced and polished to obtain epiready surfaces. The 100 mm substrates are reported with a usable area >99%. The quality of the substrates evaluated using double‐crystal X‐ray diffraction (XRD) rocking curves shows a full width of the half maximum as low as 29 arcseconds. The epiready substrates have a mean miscut <0.1°. The 100 mm AlN material demonstrates high purity with major impurity concentration being less than 10 17 cm −3 . High‐purity material aids in obtaining high‐thermal conductivity evaluated using flash technique. The AlN substrates exhibit a room‐temperature thermal conductivity of ≈290 W m −1 K −1 .