Abstract
We report on the effect of a p-type MgZnO electron blocking layer (EBL) on the electroluminescence from n-type ZnO/undoped ZnO/p-type ZnO light-emitting diodes (LEDs). The p-type Mg(0.1)Zn(0.9)O EBL was introduced between the undoped and p-type ZnO layers. The p-type Mg(0.1)Zn(0.9)O EBL increased the ultraviolet emission by 140% at 60 mA and decreased the broad deep-level emission from ZnO LEDs. The calculated band structures and carrier distribution in ZnO LEDs show that p-type Mg(0.1)Zn(0.9)O EBL effectively suppresses the electron overflow from undoped ZnO to p-type ZnO and increases the hole concentration in the undoped ZnO layer.
Highlights
Ultraviolet (UV) light-emitting diodes (LEDs) and laser diodes are attractive for their potential use in solid-state white lighting, high-density information storage, secure communications, water and air sterilization, and chemical and biological detection systems [1,2,3,4,5,6]
We report on the effect of a p-type MgZnO electron blocking layer (EBL) on the electroluminescence from n-type ZnO/undoped ZnO/ptype ZnO light-emitting diodes (LEDs)
The p-type Mg0.1Zn0.9O EBL increased the ultraviolet emission by 140% at 60 mA and decreased the broad deep-level emission from ZnO LEDs
Summary
Ultraviolet (UV) light-emitting diodes (LEDs) and laser diodes are attractive for their potential use in solid-state white lighting, high-density information storage, secure communications, water and air sterilization, and chemical and biological detection systems [1,2,3,4,5,6]. Of the available wide-bandgap semiconductors, ZnO is a promising candidate for creating efficient UV-light emitters due to its large direct bandgap of 3.37 eV, low-power threshold for optical pumping, and large exciton binding energy of 60 meV [7,8,9] These attractive properties have drawn much attention to ZnO-based homojunction LEDs [10,11,12,13]. The higher mobility of electrons than holes in ZnO LEDs causes electron overflow and increases recombination processes in the p-type ZnO region [11, 14] To overcome this problem, undoped MgZnO was introduced as an energy barrier layer to confine the recombination processes to the active layer [14]. The p-type Mg0.1Zn0.9O EBL was introduced between the undoped ZnO and p-type ZnO layer to enhance UV emission by increasing the electron and hole concentrations in the undoped ZnO active layer
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