Determination of carrier diffusion length in p- and n-type GaN

Shopan Hafiz (1) , Sebastian Metzner (2) , Fan Zhang (1) , Mortezza Monaravian (1) , Vitaly Avrutin (1) , Hadis Morkoc (1) , C Karbaum (2) , Frank Bertram (3) , Juergen Christen (2) , Bernard Gil (4) , Umit Ozgur (1)

1 VCU - Virginia Commonwealth University
2 OVGU - Otto-von-Guericke-Universität Magdeburg = Otto-von-Guericke University [Magdeburg]
3 Institute of Experimental Physics
4 L2C - Laboratoire Charles Coulomb

Diffusion lengths of photo-excited carriers along the c-direction were determined from photoluminescence (PL) measurements in p- and n-type GaN epitaxial layers grown on c-plane sapphire by metal-organic chemical vapor deposition. The investigated samples incorporate a 6 nm thick In0.15Ga0.85N active layer capped with either 500 nm p-GaN or 1300 nm n-GaN. The top GaN layers were etched in steps and PL from the InGaN active region and the underlying layers was monitored as a function of the top GaN thickness upon photogeneration near the surface region by above bandgap excitation. Taking into consideration the absorption in the active and underlying layers, the diffusion lengths at 295 K and at 15 K were measured to be about 92 +/- 7 nm and 68 +/- 7 nm for Mg-doped p-type GaN and 432 +/- 30 nm and 316 +/- 30 nm for unintentionally doped n-type GaN, respectively. Cross-sectional cathodoluminescence line-scan measurement was performed on a separate sample and the diffusion length in n-type GaN was measured to be 280 nm.

Domaines: Autre [cond-mat.other]

Shopan Hafiz, Sebastian Metzner, Fan Zhang, Mortezza Monaravian, Vitaly Avrutin, et al.. Determination of carrier diffusion length in p- and n-type GaN. GALLIUM NITRIDE MATERIALS AND DEVICES IX, Feb 2014, san francisco, France. pp.89862C, ⟨10.1117/12.2040645⟩. ⟨hal-01021440⟩