Low temperature electron mobility exceeding 104 cm2/V s in MOCVD grown β-Ga2O3

Abstract

We report on record electron mobility values measured in lightly Si doped homoepitaxial β-Ga2O3 grown by metal-organic chemical vapor deposition. The transport properties of the films were studied using temperature-dependent Hall measurements. Numerous (010) β-Ga2O3 layers grown at different conditions showed peak electron mobility exceeding 104 cm2/V s at low temperature (LT), with the highest value of 11 704 cm2/V s at 46 K. The room temperature electron mobilities of the films were between 125 cm2/V s and 160 cm2/V s with the net background charge concentration between ∼5 × 1015 cm−3 and ∼2 × 1016 cm−3. The obtained LT mobility values for β-Ga2O3 were found to be comparable to or higher than the highest LT electron mobilities in bulk SiC and GaN films in the literature. The results demonstrate the capability of metalorganic chemical vapor deposition (MOCVD) for growing high quality ultrapure β-Ga2O3 epitaxial films that are suitable for high power electronic device applications.

β‐Gallium Oxide Devices: Progress and Outlook

“…RT and low‐temperature electron μ reached 180 and 11 000 cm 2 V s −1 , respectively. [ 40–42 ] These electrical properties are comparable with those of HVPE‐grown n‐ films. Moreover, the growth rate, which used to be very slow at 0.1–0.2 μm h −1 , was enhanced to >3 μm h −1 .…”

Probing Charge Transport and Background Doping in Metal‐Organic Chemical Vapor Deposition‐Grown (010) β‐Ga2O3

“…[15][16][17] So far, MOCVD (010) β-Ga 2 O 3 exhibited high-quality epitaxy with RT Hall mobility > 170 cm 2 /V•s. [4,[18][19][20] Our previous work has demonstrated RT mobility value of 184 cm 2 /V•s on lightly Si-doped (010) thin film with an extracted low-compensation level at N A < 10 15 cm -3 . [4] The full bandgap defect state scanning via deep level transient spectroscopy/deep level optical spectroscopy (DLTS/DLOS) on our MOCVD β-Ga 2 O 3 also confirmed one order lower of total defect density as compared with bulk material or thin films grown by other techniques.…”

“…[21] Most recently, RT mobility of 130 cm 2 /V•s and low temperature (LT) peak mobility of 11700 cm 2 /V•s were reported for MOCVD grown Si-doped β-Ga 2 O 3 thin films. [19] As compared with other wide bandgap semiconductors such as SiC and GaN, the extrodinary high LT mobility in β- Among the best reported MOCVD β-Ga 2 O 3 , the n-type background concentration ranged between 10 15 cm -3 and low-10 16 cm -3 . [4,[18][19][20] The measured background carrier concentration is a result of unintentional n-type doping and low-compensation (N A ) level.…”

“…[19] As compared with other wide bandgap semiconductors such as SiC and GaN, the extrodinary high LT mobility in β- Among the best reported MOCVD β-Ga 2 O 3 , the n-type background concentration ranged between 10 15 cm -3 and low-10 16 cm -3 . [4,[18][19][20] The measured background carrier concentration is a result of unintentional n-type doping and low-compensation (N A ) level. For high power device applications, controllable doping at low levels (~10 14 cm -3 ) is desired, which requires to minimize unintentional doping level.…”

Toward Precise n-Type Doping Control in MOVPE-Grown β-Ga2O3 Thin Films by Deep-Learning Approach

“…Studies on the temperature-dependent states indicated a two-donor level, with a shallower donor energy level (ED1 = ∼10 − 35 meV) and deeper second donor (ED2 = ∼80 − 100 meV) energy levels [49][50][51]. Si is a common n-type dopant in β-Ga2O3 [52], which is predicted by the first principle of density functional theory (DFT) [53] to be a shallow donor with its preference site as a tetrahedral site Ga(I) under oxygen-rich condition due to a lower formation energy.…”