High-quality AlxGa1-xN layers with an Al composition of x=~0.4 were prepared on a GaN/sapphire substrate by a combination of controlling the growth kinetics, resulting in a slow growth rate of 5 nm/min, and introducing a stress-compensating thin AlGaN interlayer between the AlxGa1-xN and GaN layers. To control the growth kinetic activity, the reactor pressure, TMAl/TMGa flow rate, and H2/NH3 flow rate were all adjusted to obtain lessdefective and homogeneous AlxGa1-xN layers with high Al compositions, and optimized at a reactor pressure of 50 torr, TMAl/TMGa flow rate of 70/40 μmol/min, and H2/NH3 flow rate of 6/6 slpm. As a result, the sequential growth of an AlxGa1-xN layer on a 10-nm-thick AlGaN interlayer grown at 700°C on a 2.0-μm-thick GaN layer finally produced a crackfree, less defective, homogeneous Al0.33Ga0.67N film with 0.5 μm thickness. Thereafter, a typical Schottky diode of Pt/Al0.33Ga0.67N/LT-AlGaN interlayer/n+-GaN exhibited a promising electro-optical sensitivity, including a reverse leakage current of 1 nA at –5 V, UVvisible extinction ratio of ~104, and responsivity of 150 mA/W at a radiation wavelength of 280 nm.