<p>Aluminum nitride (AlN) has emerged as a promising candidate for pyroelectric sensing elements. However, systematic investigations into the performance of AlN-based pyroelectric detectors, particularly the effects of film geometry on device characteristics, remain scarce. In this study, a novel pyroelectric detector was proposed, with AlN thin films serving as the active sensing layer. The influence of film area and thickness on detector performance was systematically investigated through numerical simulations. A series of AlN-based detectors were designed and simulated using finite-element analysis. Optimization of the sensitive layer revealed that AlN exhibits superior pyroelectric properties, including a maximum current responsivity of 5.35 nA/W and voltage responsivity of 0.53&#xa0;μV/W. Notably, the responsivity values demonstrate a monotonic increase with film area but decrease with thickness. These findings highlight the critical role of geometric parameter optimization in enhancing detector performance, thereby providing a foundational framework for advancing infrared detectors.</p> Graphical abstract <p></p>