Polarization-sensitive ultraviolet photodetectors based on M-plane GaN grown on LiAlO2 substrates

Abstract

Polarization-sensitive photodetectors for the ultraviolet spectral range based on M-plane GaN films grown on LiAlO 2 substrates have been fabricated and characterized. These detectors exploit the dichroic properties of strained, M-plane GaN films. For a 400-nm-thick film, a maximum contrast of 7.25 between the detection of light polarized perpendicular and parallel to the c-axis is reached at 363 nm. Considerations for the detector design show that thin strained M-plane GaN films will enhance the polarization-sensitive bandwidth, while the maximum contrast can be obtained for relaxed thick films under weak signal detection conditions.

Light polarization sensitive photodetectors with m- and r-plane homoepitaxial ZnO/ZnMgO quantum wells

“…/R jj ) max $ 7 for m-plane PSPDs. 19 Moreover, they are also better than those previously reported for a-plane PSPDs based on ZnO QWs (PSBW $ 80 meV and (R ? /R jj ) max $ 6).…”

“…/R jj ) max $ 9.9 is reached at 3.44 eV (see inset of Figure 3), with a PSBW $ 33 meV. These figures of merit are better than the ones reported in non-polar a-and m-plane GaN-based PSPDs using bulk layers, 19,21 where the best reported values are PSBW $ 73 meV and (R ? /R jj ) max $ 7 for m-plane PSPDs.…”

“…In order to quantify the sensitivity of the photodiodes to the polarization state of the incident light, two figures of merit can be defined in addition to the responsivity above bandgap. 19 First, the shift in the absorption edge energy (DE) obtained from the responsivity when the incident light polarization is rotated 90 between the main in-plane crystallographic axes. Second, the maximum contrast ratio between the responsivities perpendicular and parallel to the main in-plane axes, given by (R ?…”

Development and prospects of nitride materials and devices with nonpolar surfaces

“…The polarized light sources do not require polarizing filters and thus the screens can be made thinner, lighter and more energy efficient. The first polarization-sensitive photodetector (PSPD) based on m-plane GaN [123] and the first very narrowband photodetector [124], combining PSPD with a polarization filter with rotated in-plane crystal orientation, have been proposed very recently, demonstrating a valuable applicability of the concept for polarization anisotropy.…”

“…This opened up the possibility for fabricating nonpolar electronic devices. MOVPE [53] PSPD [124,125] LED [53,58], LD [118 -122] MOVPE [48] HVPE [46] MOVPE [60,62] LED [48] LED [59,61], LD [123] LED [48] LED [60,62] The same group at the USC also demonstrated the first ultraviolet (UV) light-emitting diode using nonpolar a-plane GaN/AlGaN MQWs grown on r-plane sapphire [42]. Even the first experimental prototypes showed a peak emission at 363 nm with intensity almost 30 times stronger than that in the structures grown on the c-plane sapphire.…”