Thermal and mechanical characterizations of asubstrate-free focal plane array

We propose a substrate-free focal plane array (FPA) in this paper. The solid substrate is completely removed, and the microcantilevers extend from a supporting frame. Using finite element analysis, the thermal and mechanical characterizations of the substrate-free FPA are presented. Because of the large decrease in thermal conductance, the supporting frame is temperature dependent, which brings out a unique feature: the lower the thermal conductance of the supporting frame is, the higher the energy conversion efficiency in the substrate-free FPA will be. The results from the finite element analyses are consistent with our measurements: two types of substrate-free FPAs with pixel sizes of 200$\times $200 and 60$\times $60~$\mu $m$^{2}$ are implemented in the proposed infrared detector. The noise equivalent temperature difference ({NETD}) values are experimentally measured to be 520 and 300~mK respectively. Further refinements are considered in various aspects, and the substrate-free FPA with a pixel size of 30$\times $30~$\mu $m$^{2}$ has a potential of achieving an {NETD} value of 10~mK.