Ga-Doped ZnO Transparent Conductive Oxide Films Applied to GaN-Based Light-Emitting Diodes for Improving Light Extraction Efficiency

A low damage GaN-based light-emitting diode with textured/inclined sidewalls and an air–buffer layer

“…It's known that a higher surface contact resistance to p-GaN, caused by etching-induced surface damages, will yield a larger operation voltage and dynamic resistance [14]. The etching-induced surface trapping states also deteriorate the leakage current of a diode [5]. In other words, the etching process may change the surface states of a device, accordingly resulting in many current leakage paths.…”

“…Moreover, a rough mesa region on a device [4] also helps to form many escape cones where a photon could be extracted outward easily, as compared with a smooth one. However, the etching process results in degraded electrical properties, which are induced by the alternation of surface states of p-/n-GaN layers [5]. In addition, a portion of MQW layer would be sacrificed based on the mesa roughening approach [4], resulting in the increased leakage current.…”

High power GaN-based LEDs with nano-structured Ga-doped ZnO (GZO) transparent conductive layer (TCL)

“…Consequently, the recrystallization results in the reduction of electron scattering probability at the grain boundaries. Small crystallites coalesce together to form larger crystallites during the annealing process [18]. Figure 3 shows the transmission spectra of the three different kinds of contact layers.…”

Annealing-induced interfacial reactions and the effects on the electrical properties of Ga doped ZnO/CuxS contacts to p-GaN

“…In the fabrication of GaN-based LED, the p-contact with current spreading layer is considered to be one of the important factors to affect the operation voltage and emission efficiency of LED [3][4][5]. Transparent conducting oxides (TCOs) such as indium tin oxide (ITO, Sn-doped In 2 O 3 ) have been widely used as the current spreading layer of p-GaN due to their high transmittance and low resistivity [6,7].…”

“…However, the sputtering-grown ZnO contacts exhibit poor contact electrical properties with rectifying behavior [5]. In order to form ohmic contact, metal interlayers such as Ni [3], Ag [10] and Ni/Au [11] combined with ZnO have been used to form ohmic contacts to p-GaN.…”