Nitride-based light-emitting diodes with Ni/ITO p-type ohmic contacts

Abstract

The optical and electrical properties of Ni(5 nm)-Au(5 nm) and Ni(3.5 nm)-indium tin oxide (ITO) (60 nm) films were studied. It was found that the normalized transmittance of Ni/ITO film could reach 87% at 470 nm, which was much larger than that of the Ni-Au film. It was also found that the specific contact resistance was 5 10 4 cm 2 and 1 10 3 cm 2 , respectively, for Ni-Au and Ni/ITO on p-GaN. Furthermore, it was found that the 20 mA output power of light-emitting diode (LED) with Ni-Au p-contact layer was 5.26 mW. In contrast, the output power could reach 6.59 mW for the LED with Ni/ITO p-contact layer.Index Terms-GaN, light-emitting diode (LED), Ni-indium tin oxide (ITO), transparent contact.

Current-Voltage Characteristics of ITO/p-Si and ITO/n-Si Contact Interfaces

“…Indium tin oxide (ITO) layers are frequently used as front contacts in thin film optoelectronic devices such as solar cells, light emitting diodes, laser diodes, and photodectors due to their high conductivity and transparency in the visible range of the solar spectrum [1,2]. In the case of thin film solar cells, the ITO contact is necessary to allow photons to reach the absorber layer and improve the photo-generated carrier collection [3].…”

High brightness InGaN/GaN LEDs with indium‐tin‐oxide as p‐electrode

“…Samples used in this study were all grown by metalorganic chemical vapor deposition (MOCVD) [14][15][16]. To evaluate the properties of the contacts themselves, we first prepared thick p-GaN samples by depositing a 30 nm-thick low temperature GaN nucleation layer followed by a 2 µm-thick Mg-doped GaN epitaxial layer on top of the c-face (0001) sapphire substrates.…”

Au-Doped Indium Tin Oxide Ohmic Contacts to p-Type GaN

“…8 Recently, ohmic contacts based on indium tin oxide (ITO) were developed to replace the semitransparent Ni/Au contacts in GaN-based LEDs. [9][10][11][12][13][14][15] With a low electrical resistivity of $10 À4 X cm and high transmittance over the visible spectrum, ITO is widely used as a transparent conductor. However, direct deposition of ITO generally forms Schottky contacts on both n-and p-type GaN.…”

“…11 It has been found that the addition of a thin Ni interlayer can greatly improve the ohmic characteristics of ITO contacts to p-GaN. 12,13 Ni is readily transformed into NiO x , which forms a low-resistivity contact and acts as a good diffusion barrier between ITO and GaN. Ni/ITO ohmic contacts to p-GaN with specific contact resistance in the high 10 À4 X cm 2 range and transmittances over 80% at blueÀgreen wavelengths have been achieved.…”