Improved performance of near UV-blue n-ZnO/p-GaN heterostructure LED with an AlN electron blocking layer

Unal D., Varol S. F., Brault J., Chenot S., Al Khalfioui M., MERDAN Z.

MICROELECTRONIC ENGINEERING, cilt.262, 2022 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 262
  • Basım Tarihi: 2022
  • Doi Numarası: 10.1016/j.mee.2022.111830
  • Dergi Adı: MICROELECTRONIC ENGINEERING
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aerospace Database, Chemical Abstracts Core, Communication Abstracts, INSPEC, Metadex, Civil Engineering Abstracts
  • Anahtar Kelimeler: ZnO, Nitrides, Magnetron sputtering, Light emitting diode, Etching, MOCVD, E-beam evaporation, LIGHT-EMITTING-DIODES, MG-DOPED GAN, THIN-FILMS, ULTRAVIOLET ELECTROLUMINESCENCE, SUBSTRATE-TEMPERATURE, PYRAMIDAL DEFECTS, HETEROJUNCTION, NITRIDATION, ENHANCEMENT, FABRICATION
  • Gazi Üniversitesi Adresli: Evet

Özet

High quality single crystalline n-type ZnO films, with a thickness of 200 nm, were grown on top of AlN/GaN layers under 25 W, 50 W and 100 W sputtering powers. The AlN and p-type GaN layers were deposited by metalorganic chemical vapor deposition (MOCVD). From X-ray diffraction measurements, the samples exhibited the (000l) peaks corresponding to both ZnO, GaN and AlN monocrystalline layers. As the sputtering power was increased, the ZnO grain size increased and the dislocation density decreased. This result is supported by a reduction of the rms values obtained on the ZnO layers from Atomic Force Microscopy (AFM) results. In addition, photoluminescence peaks of ZnO at 372 nm, 375 nm and 380 nm were seen as dependent on the sputtering power. We have used an AlN electron blocking layer between ZnO and GaN films to improve the electroluminescence from the n-ZnO side. Room temperature electroluminescence (EL) of the LEDs demonstrated near UVblue emission consisting of predominating peaks centred at 405 nm, 390 nm and 380 nm for the device with ZnO deposited at 25 W, 50 W and 100 W sputtering powers, respectively. Moreover, the I-V curves of the LEDs showed a rectifying behavior with 6.8 V, 6.4 V, 5.2 V threshold voltages for 25 W, 50 W and 100 W values.