Low temperature growth and optical properties of α-Ga2O3 deposited on sapphire by plasma enhanced atomic layer deposition

Abstract

Plasma enhanced atomic layer deposition was used to deposit thin films of Ga2O3 on to c-plane sapphire substrates using triethylgallium and O2 plasma. The influence of substrate temperature and plasma processing parameters on the resultant crystallinity and optical properties of the Ga2O3 films were investigated. The deposition temperature was found to have a significant effect on the film crystallinity. At temperatures below 200°C amorphous Ga2O3 films were deposited. Between 250°C and 350°C the films became predominantly α-Ga2O3. Above 350°C the deposited films showed a mixture of α-Ga2O3 and ε-Ga2O3 phases. Plasma power and O2 flow rate were observed to have less influence over the resultant phases present in the films. However, both parameters could be tuned to alter the strain of the film. Ultraviolet transmittance measurements on the Ga2O3 films showed that the bandgaps ranges from 5.0 eV to 5.2 eV with the largest bandgap of 5.2 eV occurring for the α-Ga2O3 phase deposited at 250°C.

Atomic layer deposited α-Ga2O3 solar-blind photodetectors

“…A peak in response can be seen for all samples for approximately 260-280 nm illumination (this peak is more or less pronounced between the samples) and corresponds to transitions across the bandgap of α-Ga2O3. It is worth noting that this corresponds to a slightly lower energy transition than the expected bandgap [5,9,24], which may imply the presence of shallow states near the band edges. The short wavelength response links to near surface photoconduction, which appears to be enhanced in the case of anneals in argon and oxygen compared to the other samples [37].…”

“…Each ALD cycle consisted of one 0.1 s pulse of TEGa with 100 sccm of Ar carrier gas, a 5 s purge using 100 sccm Ar through the TEGa line, a 5 s 300 W O2 plasma exposure using 20 sccm O2, and finally a 5 s purge using 100 sccm Ar. These conditions of temperature, plasma power and O2 flow were found to be optimal for the growth of Ga2O3 in the α phase [24]. 2730 cycles were performed, resulting in a nominal film thickness of ca.…”

Влияние Электродов На Параметры Солнечно-Слепых Детекторов УФ Излучения

“…На сегодняшний день наиболее перспективным для производства УФ детекторов является β-Ga 2 O 3 , имеющий ширину запрещенной зоны E g ∼ 4.8 эВ. Эта модификация оксида галлия обладает высокой химической стабильностью вплоть до температуры плавления (1780 • C) [6][7][8].…”

Влияние ультрафиолетового излучения и электрического поля на проводимость структур на основе alpha- и ε-Ga-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-

“…[4]. На сегодняшний день наиболее изученным является β-Ga 2 O 3 , имеющий ширину запрещенной зоны E g ∼ 4.8 эВ, что объясняется его высокой термической и химической стабильностью [5][6][7]. β-политип оксида галлия имеет моноклинную решетку, кристаллографические характеристики которой отличны от большинства традиционных полупроводниковых подложек, таких как: сапфир, кремний, карбид кремния и др.…”