{'fraction_non_alphanumeric': 0.02815533980582524, 'fraction_numerical': 0.013592233009708738, 'mean_word_length': 5.029239766081871, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Investigation of MOCVD grown crack-free 4 μm thick aluminum nitride using nitrogen as a carrier gas

We report the growth of crack-free 4 μm thick Aluminum Nitride (AlN) layers in a custom build vertical cold wall metal–organic chemical vapor deposition (MOCVD) reactor using N2 carrier gas on 0.2° offcut sapphire substrate without any additional substrate preprocessing steps. The growth process includes a low-temperature pulsed rough buffer layer followed by a high-temperature layer with continuous growth without any interlayer. The structural properties of the AlN were analyzed using atomic force microscopy (AFM), X-ray diffraction (XRD), and Raman spectroscopy. The AFM image of the 4 µm AlN layer shows an atomically smooth 2-dimensional surface with terrace-like steps. The dislocation density of 1 × 109 cm−2 was calculated using Williamson and Hall process for a 4 µm AlN sample. Additionally, strain calculation from XRD and stress calculation from Raman spectroscopy of AlN grown with N2 carrier gas are discussed.