Gallium Nitride GaN Device Mainstream – 600V GaN D-mode HEMT Introduction

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October 28, 2021

AFor the current
gallium nitride GaN
, the proper nouns and abbreviations are as follows, which helps us understand the specifications and uses of gallium nitride GaN. This article is an introduction to gallium nitride GaN, and collects related articles from the Internet to help further understand the use of gallium nitride GaN.

HEMT : High Electron Mobility Transistors
MIS-HEMT : Metal-Insulator-Semiconductor -High Electron Mobility Transistors
E-mode GaN : Enhancement-mode GaN
D-mode GaN : Depletion-mode GaN
Gross die: 一片wafer有多少顆產品。一般而言，目前GaN wafer 是6吋晶片。
2DEG: two dimensional  electron  gas(二維電子氣通道)

We start from the gallium nitride GaN market and applications, including gallium nitride GaN process, gallium nitride GaN structure and related differences. The future gallium nitride GaN will be gallium nitride GaN on SiC and the structure is vertical. In consideration of cost and process capability, the current mainstream market is the horizontal structure of GaN on Si, and 6-inch chips are the main products.

Gallium Nitride GaN Markets, Applications, Especially in Power Electronics:

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Pradeep’s Point!

FEI STU

Gallium Nitride GaN Construction:

ResearchGate

In general gallium nitride GaN structure, current flows in gallium nitride GaN, which is also the Active Region in the figure.
In order to prevent current from flowing out of the gallium nitride GaN region, the upper and lower layers use AlGaN to prevent current overflow, that is, the insulating layer.
Active Region is also called 2DEG (two dimensional electron gas; two-dimensional electron gas channel)

Gallium nitride GaN process:

Single crystal substrate (or SiC/sapphire/Si), sapphire is mainly used for LED. Silicon carbide SiC has better and fewer defects than Si, but the manufacturing process is relatively difficult and expensive.
2DEG is the main channel and the core of GaN devices. The upper and lower layers of AlGaN are too thick, which may easily lead to poor heat dissipation.
D-mode HMET GaN: Gallium nitride GaN is a HMET (High Electron Mobility Transistors) component, its Vt is negative, that is, a normally-on element (D-mode), in general applications, we hope that the element is normally off ( E-mode), that is, the non-conduction state, which is the shortcoming of D-mode HMET. The advantage is that the Vt is relatively high and the manufacturing process is simple.
E-mode HMET GaN: In a large Fab factory, in the manufacturing process, Gate poly and implant are adjusted accordingly, and the Vt is positive. The disadvantage is that the gate leakage rises (higher gate leakage current), and the maximum Vg is about 7V.

ResearchGate

Equivalent circuits of E-mode and D-mode:

E-mode GaN D-mode GaN(Cascode)

Powerelectronicsnews

The main reason is that the Vt of D-mode GaN is negative, and an additional Mos is needed to form a normal Off. In E-mode itself, it is already normal to turn Vt positive by using manufacturing processes and other methods.