Abstract
Electrical breakdown characteristics of AlxGa1−xN buffer layers grown on Si(111) are investigated by varying the carbon concentration ([C]: from ∼1016 to 1019 cm−3), Al-composition (x = 0 and 7%), and buffer thickness (from 1.6 to 3.1 μm). A quantitative relationship between the growth conditions and carbon concentration ([C]) is established, which can guide to grow the Ga(Al)N layer with a given [C]. It is found that the carbon incorporation is sensitive to the growth temperature (T) (exponential relationship between [C] and 1/T) and the improvement of breakdown voltage by increasing [C] is observed to be limited when [C] exceeding 1019 cm−3, which is likely due to carbon self-compensation. By increasing the highly resistive (HR) Al0.07Ga0.93N buffer thickness from 1.6 to 3.1 μm, the leakage current is greatly reduced down to 1 μA/mm at a bias voltage of 1000 V.
Highlights
Due to the AlGaN/GaN heterostructure’s superior properties including high electron mobility, high sheet carrier density, and high critical electric field, this polarization-based heterostructure has been widely utilized in power switching applications under high-voltage conditions.[1,2] the employment of Si(111) substrate can lead to a low cost, the large lattice and thermal mismatches between GaN and Si(111) hinder the development of high electron mobility transistor (HEMT), especially in high power applications, wherein thick buffer is needed and low leakage current is required
Electrical breakdown characteristics of AlxGa1−xN buffer layers grown on Si(111) are investigated by varying the carbon concentration ([C]: from ∼1016 to 1019 cm−3), Al-composition (x = 0 and 7%), and buffer thickness
The employment of Si(111) substrate can lead to a low cost, the large lattice and thermal mismatches between GaN and Si(111) hinder the development of high electron mobility transistor (HEMT), especially in high power applications, wherein thick buffer is needed and low leakage current is required
Summary
Due to the AlGaN/GaN heterostructure’s superior properties including high electron mobility, high sheet carrier density, and high critical electric field, this polarization-based heterostructure has been widely utilized in power switching applications under high-voltage conditions.[1,2] the employment of Si(111) substrate can lead to a low cost, the large lattice and thermal mismatches between GaN and Si(111) hinder the development of high electron mobility transistor (HEMT), especially in high power applications, wherein thick buffer is needed and low leakage current is required. Electrical breakdown of the highly resistive (HR) buffer layer in the HEMT structure is one of the critical parameters affecting the power device reliability.[2,3]. Introduction of edge dislocation is an inferior method, which may influence the long-term reliability of HEMT device. The quantitative relationship of growth conditions on carbon incorporation and how [C] affects the electrical breakdown of HEMT device, which are still not available in literature. The adoption of AlGaN buffer is another favored method to improve the electrical breakdown performance due to its higher critical electric field than GaN (AlN ∼11.7 MV/cm, GaN∼3.5 MV/cm).[9] Here, we further investigate the impact of carbon incorporation into AlGaN buffer on the off-state breakdown voltage (VBD), which has rarely been reported for HEMT
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