Preparation of AlN:Mn films by metalorganic chemical vapor deposition for thin film electroluminescent devices

Abstract

AlN : Mn films with Mn concentrations ranging from 2 × 10 18 to 1 × 10 21 cm -3 have been prepared by metalorganic chemical vapor deposition using bismethylcyclopentadienyl-manganese as a Mn source. The films grown at 1050 °C were polycrystals, whereas those grown at substrate temperatures (T s ) lower than 800 °C were mixture of polycrystalline and amorphous AlN, with the ratio of the latter phase increasing with decreasing T s . The films showed red-orange photoluminescence based on the transitions of d-electrons in Mn 4+ ions at room temperature. The intensity of the Mn-related emission increased with decreasing T s . The T s dependence of PL was discussed in conection with the structual properties of the films. The electroluminescence (EL) properties were also investigated by fabricating thin film EL devices on glass substrates. . However, Mn-related visible luminescence has not been reported for the films grown at substrate temperatures (T s ) lower than 600 °C, where glass substrates are available.In this paper, we report preparation of AlN:Mn films by MOCVD using bismethylcyclopentadienylmanganese [(CH 3 C 5 H 4 ) 2 Mn, abbreviated as (MeCp) 2 Mn] as a Mn source. The characterization of photoluminescence (PL) focusing on the T s dependence has revealed that even the film grown at 400 °C shows bright PL at room temperature. We also demonstrate the thin film EL (TFEL) operation by fabricating the devices consisting of the AlN:Mn active layer for the first time.

Characterization of AlN:Mn thin film phosphors prepared by metalorganic chemical vapor deposition

“…The XRD patterns of both the AlN:Mn and the AlN films consisted of an intense reflection from the (0 0 0 2) plane and a week one from the (1 01 1) plane of AlN in the region of Bragg angle 2y from 30 to 45 [7]. This result indicates that the grown films were polycrystalline oriented preferentially towards the h0 0 0 1i direction of wurtzite structure.…”

“…The total thickness of the films was about 3 mm. The Mn source and the growth conditions were previously described in detail [7,8]. The Mn concentration in the films ðC Mn Þ, which were determined by X-ray microanalysis, was controlled in the region from 1 Â 10 19 to 5 Â 10 20 cm À3 by changing the carrier flow rate for The samples were characterized by double-crystal X-ray diffraction (XRD), photoluminescence (PL) and cathodoluminescence (CL).…”

“…To this effect, AlN:Mn films have been grown by several methods including molecular beam epitaxy [4], rf magnetron sputtering [5,6] and metalorganic chemical vapor deposition (MOCVD) [5,7,8]. Recently, we have achieved the growth of luminescent AlN:Mn films at substrate temperatures ðT s Þ ranging widely from 400 to 1050 1C by MOCVD [7,8]. The study has also enabled us to fabricate TFEL devices using AlN:Mn films grown on glass substrates at T s of 400 1C.…”

Analysis of the local structure of AlN:Mn using X‐ray absorption fine structure measurements

“…The possibility of constructing an electroluminescence (EL) device using this material has been suggested by the preliminary results on the EL operation of powder AlN:Mn [4,5]. Moreover, the redorange PL and EL from AlN:Mn films grown on a glass by MOCVD at the substrate temperature lower than the glass softening point of 600 ºC have been observed [6,7]. This means that it is possible to fabricate the large-area EL devices using AlN:Mn on glass.…”

“…The growth temperature was varied from 400 to 1050 °C. The detailed growth conditions have been reported elsewhere [6]. The thickness of the films was 3 µm.…”